CVE-2026-68156

Received Received - Intake

Memory Corruption in Linux Kernel Ceph Client

Publication date: 2026-08-10

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: refresh auth->authorizer_buf{,_len} after authorizer update ceph_x_create_authorizer() caches au->buf->vec.iov_base and au->buf->vec.iov_len in struct ceph_auth_handshake. These cached values are then used by the messenger connect code when sending the authorizer. ceph_x_update_authorizer() can rebuild the authorizer when a newer service ticket is available. If the rebuilt authorizer no longer fits in the existing buffer, ceph_x_build_authorizer() drops its reference to au->buf and allocates a new one. If this is the final reference, ceph_buffer_put() frees the old ceph_buffer and its vec.iov_base, but auth->authorizer_buf still points at that freed memory. A subsequent msgr1 reconnect can therefore queue the stale pointer and trigger a KASAN slab-use-after-free in _copy_from_iter() while tcp_sendmsg() copies the authorizer. Refresh auth->authorizer_buf and auth->authorizer_buf_len after a successful authorizer rebuild so the messenger sends the current buffer.

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Meta Information

Published

2026-08-10

Last Modified

2026-10-19

Generated

2026-11-08

AI Q&A

2026-08-10

EPSS Evaluated

2026-11-07

NVD

CVE-2026-68156

EUVD

EUVD-2026-55542

Affected Vendors & Products

Vendor	Product	Version / Range
ceph	ceph	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This is a use-after-free vulnerability in the Linux kernel's Ceph filesystem client. It occurs when the ceph_x_update_authorizer function rebuilds an authorizer but fails to update a cached pointer to the old buffer. This stale pointer can later be used during a reconnect, causing a slab-use-after-free when the kernel tries to copy the authorizer data.

Detection Guidance

This vulnerability is specific to the Linux kernel's Ceph client implementation and may not have direct detection commands. Monitor kernel logs for slab-use-after-free errors or Ceph-related crashes. Check for unusual network activity or failed connections in Ceph clusters.

Impact Analysis

This vulnerability could allow an attacker with access to a Ceph cluster to cause a denial of service by triggering a kernel crash. It may also potentially enable privilege escalation if combined with other vulnerabilities, though this would require specific conditions.

Compliance Impact

This vulnerability is a memory corruption issue in the Linux kernel's Ceph filesystem component. It does not directly affect compliance with standards like GDPR or HIPAA, as those focus on data protection, privacy, and security controls rather than kernel memory management flaws.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-68156. If using Ceph, ensure all clients and servers are running updated software. Restart affected services after applying updates.

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