Out-of-bounds Read Affecting kernel-rt-64k package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.38% (31st percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRT64K-19389225
  • published28 Aug 2026
  • disclosed26 Aug 2026

Introduced: 26 Aug 2026

NewCVE-2026-80557  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-64k.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k package and not the kernel-rt-64k package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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 ]

CVSS Base Scores

version 3.1