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CVE-2025-68183

Estado: AplazadaAlta (7.8)—

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

ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr

Currently when both IMA and EVM are in fix mode, the IMA signature will be reset to IMA hash if a program first stores IMA signature in security.ima and then writes/removes some other security xattr for the file.

For example, on Fedora, after booting the kernel with "ima_appraise=fix evm=fix ima_policy=appraise_tcb" and installing rpm-plugin-ima, installing/reinstalling a package will not make good reference IMA signature generated. Instead IMA hash is generated,

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This happens because when setting security.selinux, the IMA_DIGSIG flag that had been set early was cleared. As a result, IMA hash is generated when the file is closed.

Similarly, IMA signature can be cleared on file close after removing security xattr like security.evm or setting/removing ACL.

Prevent replacing the IMA file signature with a file hash, by preventing the IMA_DIGSIG flag from being reset.

Here's a minimal C reproducer which sets security.selinux as the last step which can also replaced by removing security.evm or setting ACL,

Detalles técnicos trazas, registros y código del informe original
    # getfattr -m - -d -e hex /usr/bin/bash
    # file: usr/bin/bash
    security.ima=0x0404...

    #include <stdio.h>
    #include <sys/xattr.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <string.h>
    #include <stdlib.h>

    int main() {
        const char* file_path = "/usr/sbin/test_binary";
        const char* hex_string = "030204d33204490066306402304";
        int length = strlen(hex_string);
        char* ima_attr_value;
        int fd;

        fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644);
        if (fd == -1) {
            perror("Error opening file");
            return 1;
        }

        ima_attr_value = (char*)malloc(length / 2 );
        for (int i = 0, j = 0; i < length; i += 2, j++) {
            sscanf(hex_string + i, "%2hhx", &ima_attr_value[j]);
        }

        if (fsetxattr(fd, "security.ima", ima_attr_value, length/2, 0) == -1) {
            perror("Error setting extended attribute");
            close(fd);
            return 1;
        }

        const char* selinux_value= "system_u:object_r:bin_t:s0";
        if (fsetxattr(fd, "security.selinux", selinux_value, strlen(selinux_value), 0) == -1) {
            perror("Error setting extended attribute");
            close(fd);
            return 1;
        }

        close(fd);

        return 0;
    }

CVSS

Probabilidad de explotación (EPSS)

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad local (AV:L/PR:L) que permite a un usuario con privilegios locales manipular flags IMA_DIGSIG mediante xattr, alterando firmas de archivo. Acceso local sin interacción del usuario indica escalada de privilegios (T1068). Permite modificar integridad de archivos (T1565.001) y potencialm

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Restrict File and Directory PermissionsUser TrainingThreat Intelligence ProgramPassword PoliciesRemote Data StorageExecution Prevention

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux KernelAI

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2025-68183",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "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": "e3ccfe1ad7d895487977ef64eda3441d16c9851a",
              "lessThan": "d2993a7e98eb70c737c6f5365a190e79c72b8407",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e3ccfe1ad7d895487977ef64eda3441d16c9851a",
              "lessThan": "edd824eb45e4f7e05ad3ab090dab6dbdb79cd292",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e3ccfe1ad7d895487977ef64eda3441d16c9851a",
              "lessThan": "02aa671c08a4834bef5166743a7b88686fbfa023",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e3ccfe1ad7d895487977ef64eda3441d16c9851a",
              "lessThan": "88b4cbcf6b041ae0f2fc8a34554a5b6a83a2b7cd",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "security/integrity/ima/ima_appraise.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.14"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.14",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.117",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.58",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.17.8",
              "versionType": "semver",
              "lessThanOrEqual": "6.17.*"
            },
            {
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "security/integrity/ima/ima_appraise.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-12-16T14:15:50.880",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/02aa671c08a4834bef5166743a7b88686fbfa023",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/88b4cbcf6b041ae0f2fc8a34554a5b6a83a2b7cd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d2993a7e98eb70c737c6f5365a190e79c72b8407",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/edd824eb45e4f7e05ad3ab090dab6dbdb79cd292",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Deferred",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr\n\nCurrently when both IMA and EVM are in fix mode, the IMA signature will\nbe reset to IMA hash if a program first stores IMA signature in\nsecurity.ima and then writes/removes some other security xattr for the\nfile.\n\nFor example, on Fedora, after booting the kernel with \"ima_appraise=fix\nevm=fix ima_policy=appraise_tcb\" and installing rpm-plugin-ima,\ninstalling/reinstalling a package will not make good reference IMA\nsignature generated. Instead IMA hash is generated,\n\n    # getfattr -m - -d -e hex /usr/bin/bash\n    # file: usr/bin/bash\n    security.ima=0x0404...\n\nThis happens because when setting security.selinux, the IMA_DIGSIG flag\nthat had been set early was cleared. As a result, IMA hash is generated\nwhen the file is closed.\n\nSimilarly, IMA signature can be cleared on file close after removing\nsecurity xattr like security.evm or setting/removing ACL.\n\nPrevent replacing the IMA file signature with a file hash, by preventing\nthe IMA_DIGSIG flag from being reset.\n\nHere's a minimal C reproducer which sets security.selinux as the last\nstep which can also replaced by removing security.evm or setting ACL,\n\n    #include <stdio.h>\n    #include <sys/xattr.h>\n    #include <fcntl.h>\n    #include <unistd.h>\n    #include <string.h>\n    #include <stdlib.h>\n\n    int main() {\n        const char* file_path = \"/usr/sbin/test_binary\";\n        const char* hex_string = \"030204d33204490066306402304\";\n        int length = strlen(hex_string);\n        char* ima_attr_value;\n        int fd;\n\n        fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644);\n        if (fd == -1) {\n            perror(\"Error opening file\");\n            return 1;\n        }\n\n        ima_attr_value = (char*)malloc(length / 2 );\n        for (int i = 0, j = 0; i < length; i += 2, j++) {\n            sscanf(hex_string + i, \"%2hhx\", &ima_attr_value[j]);\n        }\n\n        if (fsetxattr(fd, \"security.ima\", ima_attr_value, length/2, 0) == -1) {\n            perror(\"Error setting extended attribute\");\n            close(fd);\n            return 1;\n        }\n\n        const char* selinux_value= \"system_u:object_r:bin_t:s0\";\n        if (fsetxattr(fd, \"security.selinux\", selinux_value, strlen(selinux_value), 0) == -1) {\n            perror(\"Error setting extended attribute\");\n            close(fd);\n            return 1;\n        }\n\n        close(fd);\n\n        return 0;\n    }"
    }
  ],
  "lastModified": "2026-07-30T06:24:32.637",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}