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libceph: fix OOB read in decode_watchers() via missing bounds check

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers() via missing bounds check ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns success with p == end, leaving zero bytes guaranteed for subsequent reads. The immediately following ceph_decode_32(p) in decode_watchers() has no preceding bounds check. With p == end this is a 4-byte read past the validated buffer boundary. The garbage value is then passed directly to kzalloc_objs() as the watcher count. The sibling function decode_watcher() already uses the safe variants (ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32) after its own ceph_start_decoding() call. decode_watchers() is the only site that uses the bare variant, confirming an oversight. Fix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end, *num_watchers, bad), consistent with the established pattern. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment (e.g. cloud) can trigger this against any kernel client that calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges beyond OSD session establishment. [ idryomov: trim changelog ]

Announced Source revision 1
Original source ↗

CVE-2026-80557

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-2026-80557

Linux

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

Affected versions
Not stated in this record
Fixed versions
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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": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "85479b7d65b4ebcb07fbbe57230976793974ab4a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "1c824e7c75bb4adf19553dd4ea944a5d83096be8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "eab3eeb68bfc639d74f27256f05546af5c4f787d",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "c59219a6b62d74936963983e5815524c3de8dd79",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "cb8246e5846dbbe34930903a90c7a90dd8e5910b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
        "lessThan": "00ead17c7de137a692edee59f2772e6af687e8eb",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ceph/osd_client.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.9"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.9",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.267",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.218",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.185",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.154",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.106",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.47",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.10",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ceph/osd_client.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-80557

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#34324 · Revision 1
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Publisher date
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