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Linux Kernel EUVDEUVD-2026-38824

| CVE-2026-52956 HIGH
Out-of-bounds Read (CWE-125)
2026-06-24 Linux GHSA-wvxf-4p9h-5vg9
Buffer Overflow Information Disclosure Linux Red Hat Suse
7.5
CVSS 3.1 · Vendor: Linux
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Severity by source

Vendor (Linux) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
7.5 HIGH

Network-reachable Ceph handshake with no auth (AV:N/PR:N/UI:N); out-of-bounds read crashes the kernel, yielding availability-only impact (C:N/I:N/A:H).

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

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

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

Lifecycle Timeline

5
Analysis Generated
Jun 28, 2026 - 08:35 vuln.today
CVSS changed
Jun 28, 2026 - 08:22 NVD
7.5 (HIGH)
Patch available
Jun 24, 2026 - 18:02 EUVD
CVE Published
Jun 24, 2026 - 16:28 cve.org
HIGH 7.5
CVE Published
Jun 24, 2026 - 16:28 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()

In __ceph_x_decrypt(), a part of the buffer p is interpreted as a ceph_x_encrypt_header, and the magic field of this struct is accessed. This happens without any guarantee that the buffer is large enough to hold this struct. The function parameter ciphertext_len represents the length of the ciphertext to decrypt and is guaranteed to be at most the remaining size of the allocated buffer p. However, this value is not necessarily greater than sizeof(ceph_x_encrypt_header). E.g., a message frame of type FRAME_TAG_AUTH_REPLY_MORE, that is just as long to hold the ciphertext at its end with a ciphertext_len of 8 or less, can trigger an out-of-bounds memory access when accessing hdr->magic.

This patch fixes the issue by adding a check to ensure that the decrypted plaintext in the buffer is large enough to represent at least the ceph_x_encrypt_header.

AnalysisAI

Denial of service in the Linux kernel's libceph (Ceph client) component allows a malicious or compromised Ceph peer to crash a connecting host during the CephX authentication handshake. The flaw lives in __ceph_x_decrypt(), which reads a ceph_x_encrypt_header (notably hdr->magic) from a decrypted buffer without first verifying the buffer is large enough - a FRAME_TAG_AUTH_REPLY_MORE frame carrying a ciphertext_len of 8 or fewer bytes triggers an out-of-bounds memory access. CVSS is 7.5 (availability-only); EPSS is low at 0.16% (6th percentile), there is no public exploit identified at time of analysis, and it is not listed in CISA KEV.

Technical ContextAI

libceph is the in-kernel client library that implements the Ceph distributed-storage messaging and CephX authentication protocol used by the kernel RBD (block device) and CephFS clients. During the v2 messenger authentication exchange, __ceph_x_decrypt() decrypts an incoming frame and then casts the start of the plaintext buffer to a struct ceph_x_encrypt_header to validate its magic field. The root cause is a classic out-of-bounds read (CWE-125-class, consistent with the 'Buffer Overflow' tag) caused by a missing length check: ciphertext_len is bounded only by the remaining allocation size of buffer p, not by sizeof(ceph_x_encrypt_header), so a short AUTH_REPLY_MORE frame lets the struct field access run past valid data. The CPE data scopes this to the linux:linux kernel (cpe:2.3:a:linux:linux:*), and the fix adds a guard ensuring the decrypted plaintext is at least the size of the header struct.

RemediationAI

Vendor-released patch: update to Linux kernel 7.0.10 or 7.1 (or later), which add the length check ensuring the decrypted plaintext is at least sizeof(ceph_x_encrypt_header) before the header is dereferenced; the upstream fixes are commits c7e9b53aebe401970f1b5f5a01b4e021b18e8bb2 and 821365487aa58d06bda65c676ba215d506ba9768 (https://git.kernel.org/stable/c/c7e9b53aebe401970f1b5f5a01b4e021b18e8bb2 and https://git.kernel.org/stable/c/821365487aa58d06bda65c676ba215d506ba9768). Apply your distribution's kernel update containing these commits and reboot. Where immediate patching is not possible, reduce exposure by ensuring kernel Ceph clients only connect to trusted, authenticated Ceph monitors/OSDs over a segmented storage network and by restricting which peers can reach the client's messenger ports - note this does not fix the bug and offers no protection if the trusted Ceph cluster itself is compromised. If the host does not require kernel Ceph access, unloading/blacklisting the ceph and libceph modules eliminates the attack surface entirely, at the cost of losing RBD/CephFS kernel-client functionality.

Same weakness CWE-125 – Out-of-bounds Read

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.177 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.155 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.206 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.152 Affected
Image SLES15-SP7-Azure-3P Image SLES15-SP7-Azure-Basic Image SLES15-SP7-Azure-Standard Image SLES15-SP7-HPC-Azure Affected
Image SLES15-SP7-BYOS-Azure Image SLES15-SP7-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-Aliyun Image SLES15-SP7-CHOST-BYOS-Azure Image SLES15-SP7-CHOST-BYOS-EC2 Image SLES15-SP7-CHOST-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-GDC Image SLES15-SP7-CHOST-BYOS-SAP-CCloud Image SLES15-SP7-EC2 Image SLES15-SP7-EC2-ECS-HVM Image SLES15-SP7-GCE Image SLES15-SP7-HPC-BYOS-Azure Image SLES15-SP7-HPC-BYOS-EC2 Image SLES15-SP7-HPC-BYOS-GCE Image SLES15-SP7-Hardened-BYOS-Azure Image SLES15-SP7-Hardened-BYOS-EC2 Image SLES15-SP7-Hardened-BYOS-GCE Image SLES15-SP7-SAPCAL-Azure Image SLES15-SP7-SAPCAL-EC2 Image SLES15-SP7-SAPCAL-GCE Affected
Image SLES15-SP7-SAP-Azure Image SLES15-SP7-SAP-Azure-3P Image SLES15-SP7-SAP-BYOS-Azure Image SLES15-SP7-SAP-BYOS-EC2 Image SLES15-SP7-SAP-BYOS-GCE Image SLES15-SP7-SAP-EC2 Image SLES15-SP7-SAP-GCE Image SLES15-SP7-SAP-Hardened-Azure Image SLES15-SP7-SAP-Hardened-BYOS-Azure Image SLES15-SP7-SAP-Hardened-BYOS-EC2 Image SLES15-SP7-SAP-Hardened-BYOS-GCE Image SLES15-SP7-SAP-Hardened-GCE Affected

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EUVD-2026-38824 vulnerability details – vuln.today
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