Vulnerability-Lookup

GHSA-6PC4-H32V-99RG

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31

Details

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

memfd: deny writeable mappings when implying SEAL_WRITE

When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the implied seal is set after the check that makes sure the memfd can not have any writable mappings. This means one can use SEAL_EXEC to apply SEAL_WRITE while having writeable mappings.

This breaks the contract that SEAL_WRITE provides and can be used by an attacker to pass a memfd that appears to be write sealed but can still be modified arbitrarily.

Fix this by adding the implied seals before the call for mapping_deny_writable() is done.

Severity

8.4 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-63952"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:13Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmemfd: deny writeable mappings when implying SEAL_WRITE\n\nWhen SEAL_EXEC is added, SEAL_WRITE is implied to make W^X.  But the\nimplied seal is set after the check that makes sure the memfd can not have\nany writable mappings.  This means one can use SEAL_EXEC to apply\nSEAL_WRITE while having writeable mappings.\n\nThis breaks the contract that SEAL_WRITE provides and can be used by an\nattacker to pass a memfd that appears to be write sealed but can still be\nmodified arbitrarily.\n\nFix this by adding the implied seals before the call for\nmapping_deny_writable() is done.",
  "id": "GHSA-6pc4-h32v-99rg",
  "modified": "2026-07-20T15:31:53Z",
  "published": "2026-07-19T18:31:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63952"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0995d1f79aed8ccbf62056189dd53fd19726ea08"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3b041514cb6eae45869b020f743c14d983363222"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3be2a24f7f72ad7321ed6ad1715b956a4527bcf4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/555702282d4536a865dfffb1cd4f6028f196e7e8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3f4f82d1315f1439059a83d1c22c51a5b43d99e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-63952 (GCVE-0-2026-63952)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-20 13:41

Title

memfd: deny writeable mappings when implying SEAL_WRITE

Summary

In the Linux kernel, the following vulnerability has been resolved: memfd: deny writeable mappings when implying SEAL_WRITE When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the implied seal is set after the check that makes sure the memfd can not have any writable mappings. This means one can use SEAL_EXEC to apply SEAL_WRITE while having writeable mappings. This breaks the contract that SEAL_WRITE provides and can be used by an attacker to pass a memfd that appears to be write sealed but can still be modified arbitrarily. Fix this by adding the implied seals before the call for mapping_deny_writable() is done.

Severity

8.4 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Assigner

Linux

References

5 references

URL	Tags
https://git.kernel.org/stable/c/b3f4f82d1315f1439…
https://git.kernel.org/stable/c/3be2a24f7f72ad732…
https://git.kernel.org/stable/c/0995d1f79aed8ccbf…
https://git.kernel.org/stable/c/555702282d4536a86…
https://git.kernel.org/stable/c/3b041514cb6eae458…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: c4f75bc8bd6b3d62665e1f5400c419540edb5601 , < b3f4f82d1315f1439059a83d1c22c51a5b43d99e (git) Affected: c4f75bc8bd6b3d62665e1f5400c419540edb5601 , < 3be2a24f7f72ad7321ed6ad1715b956a4527bcf4 (git) Affected: c4f75bc8bd6b3d62665e1f5400c419540edb5601 , < 0995d1f79aed8ccbf62056189dd53fd19726ea08 (git) Affected: c4f75bc8bd6b3d62665e1f5400c419540edb5601 , < 555702282d4536a865dfffb1cd4f6028f196e7e8 (git) Affected: c4f75bc8bd6b3d62665e1f5400c419540edb5601 , < 3b041514cb6eae45869b020f743c14d983363222 (git)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.93 , ≤ 6.12.* (semver) Unaffected: 6.18.35 , ≤ 6.18.* (semver) Unaffected: 7.0.12 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/memfd.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
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              "versionType": "git"
            },
            {
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
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              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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        }
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        "dateUpdated": "2026-07-20T13:41:51.115Z",
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        {
          "url": "https://git.kernel.org/stable/c/3b041514cb6eae45869b020f743c14d983363222"
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      "title": "memfd: deny writeable mappings when implying SEAL_WRITE",
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    "datePublished": "2026-07-19T14:55:44.809Z",
    "dateReserved": "2026-07-19T07:54:57.023Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-6PC4-H32V-99RG

CVE-2026-63952 (GCVE-0-2026-63952)

Tags

Sightings

Nomenclature