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

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-20 13:41
VLAI
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
References
Impacted 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)
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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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{
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          "programFiles": [
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        }
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    "datePublished": "2026-07-19T14:55:44.809Z",
    "dateReserved": "2026-07-19T07:54:57.023Z",
    "dateUpdated": "2026-07-20T13:41:51.115Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-21T17:31:04+00:00",
      "cve": "CVE-2026-63952",
      "id": "CVE-2026-63952",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: memfd: deny writeable mappings when implying SEAL_WRITE",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63952.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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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.


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