CVE-2025-21910

Estado: ModificadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

wifi: cfg80211: regulatory: improve invalid hints checking

Syzbot keeps reporting an issue [1] that occurs when erroneous symbols sent from userspace get through into user_alpha2[] via regulatory_hint_user() call. Such invalid regulatory hints should be rejected.

While a sanity check from commit 47caf685a685 ("cfg80211: regulatory: reject invalid hints") looks to be enough to deter these very cases, there is a way to get around it due to 2 reasons.

1) The way isalpha() works, symbols other than latin lower and upper letters may be used to determine a country/domain.

Leer descripción completaMostrar menos

For instance, greek letters will also be considered upper/lower letters and for such characters isalpha() will return true as well. However, ISO-3166-1 alpha2 codes should only hold latin characters.

2) While processing a user regulatory request, between reg_process_hint_user() and regulatory_hint_user() there happens to be a call to queue_regulatory_request() which modifies letters in request->alpha2[] with toupper(). This works fine for latin symbols, less so for weird letter characters from the second part of _ctype[].

Syzbot triggers a warning in is_user_regdom_saved() by first sending over an unexpected non-latin letter that gets malformed by toupper() into a character that ends up failing isalpha() check.

Prevent this by enhancing is_an_alpha2() to ensure that incoming symbols are latin letters and nothing else.

Detalles técnicos trazas, registros y código del informe original

[1] Syzbot report:
------------[ cut here ]------------
Unexpected user alpha2: A�
WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline]
WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline]
WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516
Modules linked in:
CPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_power_efficient crda_timeout_work
RIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline]
RIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline]
RIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516
...
Call Trace:
 <TASK>
 crda_timeout_work+0x27/0x50 net/wireless/reg.c:542
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Puntuación base: 5.5

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.23%
Percentil entre todas las CVEs puntuadas: 12
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2025-21910",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "da3f599517ef2ea851208df3229d07728d238dc5",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "6a5e3b23054cee3b92683d1467e3fa83921f5622",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "f4112cb477c727a65787a4065a75ca593bb5b2f4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "35ef07112b61b06eb30683a6563c9f6378c02476",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "be7c5f00aa7f1344293e4d48d0e12be83a2f223d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "17aa34c84867f6cd181a5743e1c647e7766962a6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "09d989d179d0c679043556dda77c51b41a2dae7e",
              "lessThan": "59b348be7597c4a9903cb003c69e37df20c04a30",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/wireless/reg.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.34"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.34",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.4.291",
              "versionType": "semver",
              "lessThanOrEqual": "5.4.*"
            },
            {
              "status": "unaffected",
              "version": "5.10.235",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.179",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.131",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.83",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.19",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.13.7",
              "versionType": "semver",
              "lessThanOrEqual": "6.13.*"
            },
            {
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/wireless/reg.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-04-01T16:15:21.550",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/17aa34c84867f6cd181a5743e1c647e7766962a6",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/35ef07112b61b06eb30683a6563c9f6378c02476",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/59b348be7597c4a9903cb003c69e37df20c04a30",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6a5e3b23054cee3b92683d1467e3fa83921f5622",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/be7c5f00aa7f1344293e4d48d0e12be83a2f223d",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/da3f599517ef2ea851208df3229d07728d238dc5",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f4112cb477c727a65787a4065a75ca593bb5b2f4",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: cfg80211: regulatory: improve invalid hints checking\n\nSyzbot keeps reporting an issue [1] that occurs when erroneous symbols\nsent from userspace get through into user_alpha2[] via\nregulatory_hint_user() call. Such invalid regulatory hints should be\nrejected.\n\nWhile a sanity check from commit 47caf685a685 (\"cfg80211: regulatory:\nreject invalid hints\") looks to be enough to deter these very cases,\nthere is a way to get around it due to 2 reasons.\n\n1) The way isalpha() works, symbols other than latin lower and\nupper letters may be used to determine a country/domain.\nFor instance, greek letters will also be considered upper/lower\nletters and for such characters isalpha() will return true as well.\nHowever, ISO-3166-1 alpha2 codes should only hold latin\ncharacters.\n\n2) While processing a user regulatory request, between\nreg_process_hint_user() and regulatory_hint_user() there happens to\nbe a call to queue_regulatory_request() which modifies letters in\nrequest->alpha2[] with toupper(). This works fine for latin symbols,\nless so for weird letter characters from the second part of _ctype[].\n\nSyzbot triggers a warning in is_user_regdom_saved() by first sending\nover an unexpected non-latin letter that gets malformed by toupper()\ninto a character that ends up failing isalpha() check.\n\nPrevent this by enhancing is_an_alpha2() to ensure that incoming\nsymbols are latin letters and nothing else.\n\n[1] Syzbot report:\n------------[ cut here ]------------\nUnexpected user alpha2: A�\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\nModules linked in:\nCPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: events_power_efficient crda_timeout_work\nRIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline]\nRIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline]\nRIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\n...\nCall Trace:\n <TASK>\n crda_timeout_work+0x27/0x50 net/wireless/reg.c:542\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f2/0x390 kernel/kthread.c:389\n ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n </TASK>"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: wifi: cfg80211: regulatory: improve invalid hints checking Syzbot sigue reportando un problema [1] que ocurre cuando símbolos erróneos enviados desde el espacio de usuario se introducen en user_alpha2[] mediante la llamada regulatory_hint_user(). Estas sugerencias regulatorias inválidas deben rechazarse. Si bien una comprobación de seguridad del commit 47caf685a685 (\"cfg80211: regulatory: reject invalid hints\") parece ser suficiente para evitar estos casos, existe una forma de evitarla por dos razones: 1) El funcionamiento de isalpha() permite usar símbolos distintos de las letras latinas mayúsculas y minúsculas para determinar un país o dominio. Por ejemplo, las letras griegas también se considerarán mayúsculas y minúsculas, y para estos caracteres isalpha() también devolverá verdadero. Sin embargo, los códigos ISO-3166-1 alpha2 solo deben contener caracteres latinos. 2) Al procesar una solicitud regulatoria de usuario, entre reg_process_hint_user() y regulatory_hint_user() se produce una llamada a queue_regulatory_request() que modifica las letras en request-&gt;alpha2[] con toupper(). Esto funciona correctamente con símbolos latinos, pero no tanto con caracteres de letras extrañas de la segunda parte de _ctype[]. Syzbot genera una advertencia en is_user_regdom_saved() al enviar primero una letra no latina inesperada que toupper() malforma en un carácter que falla la comprobación de isalpha(). Para evitar esto, mejore is_an_alpha2() para garantizar que los símbolos entrantes sean únicamente letras latinas. [1] Informe de Syzbot: ------------[ cortar aquí ]------------ Usuario inesperado alpha2: A? ADVERTENCIA: CPU: 1 PID: 964 en net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [en línea] ADVERTENCIA: CPU: 1 PID: 964 en net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [en línea] ADVERTENCIA: CPU: 1 PID: 964 en net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516 Módulos vinculados: CPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 No contaminado 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0 Nombre del hardware: Google Google Compute Engine/Google Compute Engine, BIOS Google 13/09/2024 Cola de trabajo: events_power_efficient crda_timeout_work RIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [en línea] RIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [en línea] RIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516 ... Rastreo de llamadas:  crda_timeout_work+0x27/0x50 net/wireless/reg.c:542 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f2/0x390 kernel/kthread.c:389 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244  "
    }
  ],
  "lastModified": "2026-06-17T08:44:35.277",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "EED05E52-7CFA-4A43-A352-40F047FDB63A",
              "versionEndExcluding": "5.4.291",
              "versionStartIncluding": "2.6.34"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "545121FA-DE31-4154-9446-C2000FB4104D",
              "versionEndExcluding": "5.10.235",
              "versionStartIncluding": "5.5"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "C708062C-4E1B-465F-AE6D-C09C46400875",
              "versionEndExcluding": "5.15.179",
              "versionStartIncluding": "5.11"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "BA9C2DE3-D37C-46C6-8DCD-2EE509456E0B",
              "versionEndExcluding": "6.1.131",
              "versionStartIncluding": "5.16"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "7D9F642F-6E05-4926-B0FE-62F95B7266BC",
              "versionEndExcluding": "6.6.83",
              "versionStartIncluding": "6.2"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "32865E5C-8AE1-4D3D-A64D-299039694A88",
              "versionEndExcluding": "6.12.19",
              "versionStartIncluding": "6.7"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "842F5A44-3E71-4546-B4FD-43B0ACE3F32B",
              "versionEndExcluding": "6.13.7",
              "versionStartIncluding": "6.13"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "66619FB8-0AAF-4166-B2CF-67B24143261D"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "D3D6550E-6679-4560-902D-AF52DCFE905B"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "45B90F6B-BEC7-4D4E-883A-9DBADE021750"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}