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Linux Kernel EUVDEUVD-2026-55542

| CVE-2026-68156 CRITICAL
2026-08-10 Linux GHSA-rf74-56p2-8jqj
Information Disclosure Linux Suse
Critical
Disputed · 9.8 Vendor: Linux
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Severity by source

Sources disagree (Medium–Critical)
Vendor (Linux) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
6.5 MEDIUM

Network-reachable but needs attacker-influenced ticket rotation, msgr1, and precise free/reconnect timing (AC:H); impact is mainly client crash (A:H) with limited freed-memory leak (C:L), no integrity impact.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
6.5 MEDIUM
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
Red Hat
7.0 MEDIUM
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 14, 2026 - 02:35 vuln.today
CVSS changed
Aug 13, 2026 - 23:37 NVD
9.8 (CRITICAL)
Patch available
Aug 10, 2026 - 14:18 EUVD
CVE Published
Aug 10, 2026 - 11:59 cve.org
CRITICAL 9.8
CVE Published
Aug 10, 2026 - 11:59 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

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.

AnalysisAI

Use-after-free in the Linux kernel's libceph (Ceph client) authentication code lets a stale pointer to a freed ceph_buffer be transmitted during a msgr1 reconnect, triggering a KASAN slab-use-after-free in _copy_from_iter() as tcp_sendmsg() copies the authorizer. The flaw affects hosts acting as Ceph clients (RBD, CephFS, rados) and can crash the client kernel and potentially leak freed slab memory over the wire. It is patched upstream; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.

Technical ContextAI

The bug lives in libceph's CephX authentication handshake. ceph_x_create_authorizer() caches the authorizer buffer pointer and length (au->buf->vec.iov_base / iov_len) into struct ceph_auth_handshake, and the messenger connect path later uses those cached values to send the authorizer. When a newer service ticket arrives, ceph_x_update_authorizer() may rebuild the authorizer via ceph_x_build_authorizer(); if the rebuilt authorizer no longer fits the existing buffer, the old ceph_buffer is dropped and a new one allocated. If that was the final reference, ceph_buffer_put() frees the old buffer and its vec.iov_base, but auth->authorizer_buf/authorizer_buf_len still point at the freed memory. This is a classic use-after-free (CWE-416); the CWE field was supplied as N/A but the description unambiguously describes a dangling-pointer free/reuse. The fix refreshes auth->authorizer_buf{,_len} after a successful rebuild so the messenger sends the current buffer. CPE data identifies the affected product only generically as cpe:2.3:a:linux:linux, i.e. the mainline kernel.

RemediationAI

Vendor-released patch: upgrade to a fixed stable kernel - 6.6.148, 6.12.101, 6.18.42, or 7.1.6 (mainline 7.2-rc5), or apply the backported stable commits (e.g. https://git.kernel.org/stable/c/9d37aec9ffe4e743dabc3f84502e9723e17a30d4 and the other listed commits) if you maintain your own kernel tree. Where immediate patching is not possible, reduce exposure by migrating Ceph clients to the msgr2 protocol (ms_mode=secure/crc), since the described trigger path is the msgr1 reconnect flow - with the trade-off that all cluster peers must support msgr2. Additionally, treat the Ceph cluster network as a trust boundary: restrict which monitors/OSDs clients connect to, enforce network segmentation and authenticated/encrypted messenger transport so a rogue peer cannot drive ticket rotation, accepting the operational overhead of tighter network policy. These are compensating controls only; the buffer-refresh fix in the patch is the actual remediation.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

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EUVD-2026-55542 vulnerability details – vuln.today
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