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CVE-2026-89634 (GCVE-0-2026-89634)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01
VLAI
Title
smb: client: fix ALIGN() overflow in symlink_data() error context loop
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix ALIGN() overflow in symlink_data() error context loop The check added by commit 7d9a7f1f96cd ("smb/client: fix possible infinite loop and oob read in symlink_data()") compared the post-ALIGN length against the remaining buffer, but ALIGN() itself can overflow: for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8) wraps to 0, so the subsequent bounds check passes, and the loop advances by zero bytes leaving 'p' pointing into stale data. Fix by checking the raw ErrorDataLength against the remaining space before applying ALIGN(), then checking again after. Since raw_len is bounded by the buffer, raw_len + 7 cannot overflow, so the second check is an exact post-alignment bounds guard.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < 2b4a25baa0b936fef6915c0459925077b324ecaf (git)
Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < b89d678f9eafcf8d74885983166ba26b40a04ea0 (git)
Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < 657372ba6ea50b4474d2a6a610097eae8cd1f3e9 (git)
Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < 1f824f61d1df52392eaf0b74dfa5659d724fde30 (git)
Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < 62a3025983c8c735a3c6fc85a59316f31b59af07 (git)
Affected: 76894f3e2f71177747b8b4763fb180e800279585 , < 62656b024efc21c3230eade1a847f25871c3d2bb (git)
Affected: 2d046892a493d9760c35fdaefc3017f27f91b621 (git)
Affected: 6.0.16 , < 6.1 (semver)
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Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix ALIGN() overflow in symlink_data() error context loop\n\nThe check added by commit 7d9a7f1f96cd (\"smb/client: fix possible\ninfinite loop and oob read in symlink_data()\") compared the post-ALIGN\nlength against the remaining buffer, but ALIGN() itself can overflow:\nfor ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8)\nwraps to 0, so the subsequent bounds check passes, and the loop\nadvances by zero bytes leaving \u0027p\u0027 pointing into stale data.\n\nFix by checking the raw ErrorDataLength against the remaining space\nbefore applying ALIGN(), then checking again after.  Since raw_len is\nbounded by the buffer, raw_len + 7 cannot overflow, so the second check\nis an exact post-alignment bounds guard."
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89634",
    "datePublished": "2026-09-11T19:45:28.823Z",
    "dateReserved": "2026-09-11T19:38:34.739Z",
    "dateUpdated": "2026-09-14T12:01:40.637Z",
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Since raw_len is\\nbounded by the buffer, raw_len + 7 cannot overflow, so the second check\\nis an exact post-alignment bounds guard.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/smb2file.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"2b4a25baa0b936fef6915c0459925077b324ecaf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"b89d678f9eafcf8d74885983166ba26b40a04ea0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"657372ba6ea50b4474d2a6a610097eae8cd1f3e9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"1f824f61d1df52392eaf0b74dfa5659d724fde30\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"62a3025983c8c735a3c6fc85a59316f31b59af07\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"76894f3e2f71177747b8b4763fb180e800279585\",\"lessThan\":\"62656b024efc21c3230eade1a847f25871c3d2bb\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2d046892a493d9760c35fdaefc3017f27f91b621\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6.0.16\",\"lessThan\":\"6.1\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/client/smb2file.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.188\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.157\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H\",\"baseScore\":9.1,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1f824f61d1df52392eaf0b74dfa5659d724fde30\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2b4a25baa0b936fef6915c0459925077b324ecaf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/62656b024efc21c3230eade1a847f25871c3d2bb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/62a3025983c8c735a3c6fc85a59316f31b59af07\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/657372ba6ea50b4474d2a6a610097eae8cd1f3e9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b89d678f9eafcf8d74885983166ba26b40a04ea0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-14T19:27:16+00:00",
      "cve": "CVE-2026-89634",
      "id": "CVE-2026-89634",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "185",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix ALIGN() overflow in symlink_data() error context loop",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89634.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.

Sightings

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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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