CVE-2026-80561
Received Received - Intake

Heap-based Buffer Overflow in Linux Kernel Ceph Client

Publication date: 2026-08-26

Last updated on: 2026-08-26

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: libceph: fix multiple unsafe decodes in decode_locker() decode_locker() in cls_lock_client.c contains three unsafe decode operations that allow a malicious or compromised OSD to trigger slab-out-of-bounds reads: 1. ceph_decode_copy() at the locker_id_t name field has no preceding bounds check. With p == end after ceph_start_decoding() accepts struct_len=0, this reads sizeof(ceph_entity_name) = 9 bytes past the validated buffer boundary. 2. *p += sizeof(struct ceph_timespec) after the locker_info_t header is an unchecked pointer advance. A malicious OSD can position p past end, causing all subsequent _safe checks to pass against a bogus boundary. 3. len = ceph_decode_32(p) has no preceding bounds check, and the immediately following *p += len is uncapped. A malicious OSD can send len=0xffffffff, advancing p gigabytes past end and escaping the decode window entirely. Fix all three by replacing bare operations with their safe variants: ceph_decode_copy -> ceph_decode_copy_safe *p += sizeof(...) -> ceph_decode_skip_n ceph_decode_32(p) -> ceph_decode_32_safe *p += len -> ceph_decode_skip_n A new label is added to return -EINVAL on any bounds violation. -EINVAL is appropriate here: the data received from the OSD is structurally malformed, which is an invalid argument to the decode contract regardless of whether the caller or the wire is at fault. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any kernel client that issues the lock.get_info class method (e.g. during RBD exclusive lock acquisition) without any further privileges beyond OSD session establishment. [ idryomov: use ceph_decode_skip_string() to skip description, trim changelog ]

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Meta Information

Published
2026-08-26
Last Modified
2026-08-26
Generated
2026-08-26
AI Q&A
2026-08-26
EPSS Evaluated
N/A
NVD
CVE-2026-80561
EUVD
EUVD-2026-66476

Affected Vendors & Products

Currently, no data is known.

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves unsafe decode operations in the libceph component. Specifically, the decode_locker() function in cls_lock_client.c performs three unsafe operations that allow a malicious or compromised OSD (Object Storage Daemon) to trigger slab-out-of-bounds reads. These operations lack proper bounds checking, enabling an attacker to read beyond the intended buffer and potentially cause memory corruption.

Detection Guidance

This vulnerability is specific to the Linux kernel's Ceph client implementation and requires detecting unsafe decode operations in cls_lock_client.c. There are no direct network or system commands to detect this vulnerability as it involves kernel-level memory corruption triggered by malicious OSD messages. Monitoring kernel logs for slab-out-of-bounds errors or crashes during Ceph operations may indicate exploitation. Ensure your kernel is updated to a patched version.

Impact Analysis

If you are using a Linux kernel with Ceph storage and the vulnerable libceph component, a malicious OSD in your deployment could exploit this flaw. This could lead to memory corruption, crashes, or potential code execution on systems issuing lock.get_info class methods, such as during RBD exclusive lock acquisition. The impact depends on the privileges of the affected system.

Mitigation Strategies

Immediately update your Linux kernel to a version containing the fix for CVE-2026-80561. If updating is not immediately possible, restrict access to Ceph OSDs to trusted entities only. Disable the lock.get_info class method if not required. Monitor kernel logs for suspicious activity and consider isolating Ceph clients until patched.

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