CVE-2025-21820
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
tty: xilinx_uartps: split sysrq handling
lockdep detects the following circular locking dependency:
The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock.
Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock.
Detalles técnicos trazas, registros y código del informe original
CPU 0 CPU 1
========================== ============================
cdns_uart_isr() printk()
uart_port_lock(port) console_lock()
cdns_uart_console_write()
if (!port->sysrq)
uart_port_lock(port)
uart_handle_break()
port->sysrq = ...
uart_handle_sysrq_char()
printk()
console_lock()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: 0.17%
- Percentil entre todas las CVEs puntuadas: 5
- 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)
CWE
- CWE-667
Referencias
- https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3
- https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c
- https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2
- https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe
- https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065
- https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
JSON original (NVD)
Mostrar
{
"id": "CVE-2025-21820",
"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": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "e22a97700901ba5e8bf8db68056a0d50f9440cae",
"versionType": "git"
},
{
"status": "affected",
"version": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "de5bd24197bd9ee37ec1e379a3d882bbd15c5065",
"versionType": "git"
},
{
"status": "affected",
"version": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c",
"versionType": "git"
},
{
"status": "affected",
"version": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "9b88a7c4584ba67267a051069b8abe44fc9595b2",
"versionType": "git"
},
{
"status": "affected",
"version": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "4410dba9807a17a93f649a9f5870ceaf30a675a3",
"versionType": "git"
},
{
"status": "affected",
"version": "74ea66d4ca061a3cd4c0e924e51b60e924644852",
"lessThan": "b06f388994500297bb91be60ffaf6825ecfd2afe",
"versionType": "git"
}
],
"programFiles": [
"drivers/tty/serial/xilinx_uartps.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.6"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.6",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.15.179",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.129",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.78",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.14",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.13.3",
"versionType": "semver",
"lessThanOrEqual": "6.13.*"
},
{
"status": "unaffected",
"version": "6.14",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/tty/serial/xilinx_uartps.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-02-27T20:16:04.520",
"references": [
{
"url": "https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html",
"source": "af854a3a-2127-422b-91ae-364da2661108"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-667"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: xilinx_uartps: split sysrq handling\n\nlockdep detects the following circular locking dependency:\n\nCPU 0 CPU 1\n========================== ============================\ncdns_uart_isr() printk()\n uart_port_lock(port) console_lock()\n\t\t\t cdns_uart_console_write()\n if (!port->sysrq)\n uart_port_lock(port)\n uart_handle_break()\n port->sysrq = ...\n uart_handle_sysrq_char()\n printk()\n console_lock()\n\nThe fixed commit attempts to avoid this situation by only taking the\nport lock in cdns_uart_console_write if port->sysrq unset. However, if\n(as shown above) cdns_uart_console_write runs before port->sysrq is set,\nthen it will try to take the port lock anyway. This may result in a\ndeadlock.\n\nFix this by splitting sysrq handling into two parts. We use the prepare\nhelper under the port lock and defer handling until we release the lock."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tty: xilinx_uartps: la gestión dividido de sysrq lockdep detecta la siguiente dependencia de bloqueo circular: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. Sin embargo, si (como se muestra arriba) cdns_uart_console_write se ejecuta antes de que port->sysrq esté configurado, entonces intentará tomar el bloqueo del puerto de todos modos. Esto puede resultar en un bloqueo. Solucione esto dividiendo la gestión de sysrq en dos partes. Usamos el asistente de preparación bajo el bloqueo del puerto y posponemos la gestión hasta que liberemos el bloqueo."
}
],
"lastModified": "2026-06-17T08:44:22.597",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "931829B0-EF08-4EA8-A30B-4A6456FC70A0",
"versionEndExcluding": "6.1.129",
"versionStartIncluding": "4.6"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "0C58261F-EDFB-4A12-8CCD-F12101482030",
"versionEndExcluding": "6.6.78",
"versionStartIncluding": "6.2"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "033BB7EE-C9A2-45EA-BAC9-87BB9D951BCD",
"versionEndExcluding": "6.12.14",
"versionStartIncluding": "6.7"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "0E92CEE3-1FC3-4AFC-A513-DEDBA7414F00",
"versionEndExcluding": "6.13.3",
"versionStartIncluding": "6.13"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}