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smb: client: fix OOB reads parsing symlink error response

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB reads parsing symlink error response When a CREATE returns STATUS_STOPPED_ON_SYMLINK, smb2_check_message() returns success without any length validation, leaving the symlink parsers as the only defense against an untrusted server. symlink_data() walks SMB 3.1.1 error contexts with the loop test "p < end", but reads p->ErrorId at offset 4 and p->ErrorDataLength at offset 0. When the server-controlled ErrorDataLength advances p to within 1-7 bytes of end, the next iteration will read past it. When the matching context is found, sym->SymLinkErrorTag is read at offset 4 from p->ErrorContextData with no check that the symlink header itself fits. smb2_parse_symlink_response() then bounds-checks the substitute name using SMB2_SYMLINK_STRUCT_SIZE as the offset of PathBuffer from iov_base. That value is computed as sizeof(smb2_err_rsp) + sizeof(smb2_symlink_err_rsp), which is correct only when ErrorContextCount == 0. With at least one error context the symlink data sits 8 bytes deeper, and each skipped non-matching context shifts it further by 8 + ALIGN(ErrorDataLength, 8). The check is too short, allowing the substitute name read to run past iov_len. The out-of-bound heap bytes are UTF-16-decoded into the symlink target and returned to userspace via readlink(2). Fix this all up by making the loops test require the full context header to fit, rejecting sym if its header runs past end, and bound th

Announced Source revision 1
Original source ↗

CVE-2026-31613

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-31613

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "043834e72337ee7b4e9685859888623ba1504ac7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "d65a64755a3df68a2fd19d2a81395e9f723aca23",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "20ac98f0eb6047edb73c9a27af782bdde08b3757",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "e0dd90d14cbbf318157ea8e3fb62ee68a28655ed",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "781902e069f4ecb6c3b83502f181972c1446110a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "a66ef2e7ed837325c5600f8617d5ee0a0a149fdd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "76894f3e2f71177747b8b4763fb180e800279585",
        "lessThan": "3df690bba28edec865cf7190be10708ad0ddd67e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2d046892a493d9760c35fdaefc3017f27f91b621",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.0.16",
        "lessThan": "6.1",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/smb/client/smb2file.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "6.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.175",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.141",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.91",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.24",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.14",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.1",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/smb/client/smb2file.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31613

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#39931 · Revision 1
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Publisher date
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