libceph: fix OOB read in decode_watchers() via missing bounds check
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 ]
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
- Not stated in this record
- Prerequisites
- Not stated in this record
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",
"version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
"lessThan": "eab3eeb68bfc639d74f27256f05546af5c4f787d",
"versionType": "git"
},
{
"status": "affected",
"version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
"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
- Added to Heist Feed
- Publisher date