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Linux Kernel CVE-2026-68160

| EUVDEUVD-2026-55546 CRITICAL
Out-of-bounds Read (CWE-125)
2026-08-10 Linux GHSA-prf2-r76g-87fc
9.8
CVSS 3.1 · Vendor: Linux
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Compromise or impersonate Ceph MDS
  2. Delivery
    Craft caps message hdr.version=1
  3. Exploit
    Set snap_trace_len 0xFFFFFFFF on IMPORT
  4. Execution
    Client decodes fake snap realm
  5. Persist
    Read kernel memory past front buffer
  6. Impact
    Leak data or panic client

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the target to be running the Linux CephFS kernel client and actively communicating with the attacker-controlled component - specifically a malicious or compromised Ceph MDS (or an on-path attacker able to forge MDS traffic). The concrete trigger is a ceph_mds_caps message carrying the CEPH_CAP_OP_IMPORT op with msg->hdr.version deliberately set to 1 (which bypasses the msg_version>=2 decoders) and an oversized snap_trace_len such as 0xFFFFFFFF. Limiting factors: the host must mount or be mounting CephFS, the attacker must sit in the client's server trust relationship, and the primitive is an out-of-bounds read (memory disclosure/DoS) rather than direct code execution. Hosts that never use CephFS are not exploitable regardless of the network-facing CVSS metric.

Impact

The raw CVSS of 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) overstates real-world exposure and should be read critically. The attack is not a generic remote exploit against any Linux host: it requires the victim to be a CephFS client connected to a malicious or compromised MDS, so the practical threat model is a subverted storage cluster or a man-in-the-middle on the Ceph control plane, not an arbitrary internet attacker. The primary primitive is an out-of-bounds read, which realistically yields kernel memory disclosure and denial of service (panic) rather than the clean integrity/RCE impact the I:H metric implies - I would rate integrity impact lower than the feed's vector. Corroborating this, EPSS is only 0.22% (12th percentile), there is no CISA KEV listing and no public PoC, indicating no observed exploitation. That said, for any organization actually running CephFS at scale, a single compromised MDS can read kernel memory from every mounting client, so the blast radius within a Ceph deployment is significant and patching should not be deferred. The bottom line: high severity for CephFS operators, low priority for hosts that never mount CephFS.

Exploit ScenarioDerived

An attacker who has compromised a Ceph Metadata Server (or can impersonate one on the storage network) sends a crafted CEPH_CAP_OP_IMPORT caps message with hdr.version=1 and snap_trace_len=0xFFFFFFFF to a connected CephFS client. The client's ceph_update_snap_trace() decodes a bogus snap realm well past the message buffer, leaking adjacent kernel memory or panicking the host. No public PoC is currently known, and the network attack vector with low complexity means no user interaction is needed once the malicious server is in the client's trust path.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 14, 2026

Pre-authentication out-of-bounds kernel memory read in the Linux kernel's CephFS client (ceph_handle_caps) allows a malicious or compromised Ceph Metadata Server (MDS) to read beyond the message front buffer. By sending a CEPH_CAP_OP_IMPORT caps message with hdr.version set to 1 and an oversized snap_trace_len (e.g. 0xFFFFFFFF), the server bypasses all version-gated decoders and drives ceph_update_snap_trace() to decode a fake snap realm past the buffer, cascading into further OOB reads via attacker-controlled num_snaps/num_prior_parent_snaps counts. The flaw is present in every kernel since ceph_handle_caps() was introduced; it carries a CVSS 9.8 but currently has no public exploit and a low EPSS score (0.22%), and it is not on CISA KEV.

RemediationAI

Vendor-released patch: upgrade to a fixed stable kernel - 6.6.148, 6.12.101, 6.18.42, 7.1.6, or 7.2-rc5 or later - or apply your distribution's backport (e.g. the Canonical/Ubuntu update). The upstream fixes are available as stable commits: https://git.kernel.org/stable/c/9081c71796724ffe96cba253f68fbe42363c5295, https://git.kernel.org/stable/c/03b417afce19ee6b6e61f1bbbbebac924c9f36d1, https://git.kernel.org/stable/c/a4228b93706fb74a484e6ffb271c1cc2af3a2ddb, https://git.kernel.org/stable/c/71893c342a26bcff92eaab0b2b75d64aed19308a, and https://git.kernel.org/stable/c/4dbc71bcaf9a30abf3920a4e2cc4ed33bba78c02. Where immediate patching is not possible, reduce exposure by ensuring CephFS clients only connect to trusted, hardened MDS nodes over authenticated cephx and network-isolated storage VLANs, and unmount CephFS on hosts that do not require it (side effect: those hosts lose CephFS access). Enabling cephx authentication and msgr2 secure mode raises the bar against MDS spoofing/MITM but does not protect against a genuinely compromised MDS, so patching remains the only complete fix.

Affected VersionsENISA

Linux patch: 0
Linux patch: 6.12.101
Linux patch: 7.1.6
Linux patch: 7.2-rc5
Linux patch: 6.6.148
Linux patch: 6.18.42
Linux a8599bd821d084d04a3290fffae1071624ec00ea <9081c71796724ffe96cba253f68fbe42363c5295
Linux a8599bd821d084d04a3290fffae1071624ec00ea <71893c342a26bcff92eaab0b2b75d64aed19308a
Linux a8599bd821d084d04a3290fffae1071624ec00ea <4dbc71bcaf9a30abf3920a4e2cc4ed33bba78c02
Linux a8599bd821d084d04a3290fffae1071624ec00ea <a4228b93706fb74a484e6ffb271c1cc2af3a2ddb
Linux 2.6.34
Linux a8599bd821d084d04a3290fffae1071624ec00ea <03b417afce19ee6b6e61f1bbbbebac924c9f36d1

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability lives in the kernel CephFS client, which speaks the Ceph wire protocol to a cluster's Metadata Servers. In ceph_handle_caps() the code reads snap_trace_len directly from the wire-format ceph_mds_caps header and builds an end pointer as snaptrace + snaptrace_len without validating that length against the actual msg->front buffer size. The eleven msg_version >= 2..12 decoder blocks that would normally catch this sit behind an hdr.version gate, so a message declaring version 1 skips all of them and reaches the op switch with an unvalidated length. This is a classic out-of-bounds read (CWE-125, though CWE is marked N/A in the feed) rooted in trusting an attacker-supplied length field; on 32-bit builds the naive p + snap_trace_len addition can also wrap the address space. The fix validates snap_trace_len with the canonical ceph_decode_need()/ceph_has_room() helper, which bounds via subtraction (n <= end - p) rather than pointer addition, making it wrap-safe.

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Severity by source

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 9.1 CRITICAL

Remote malicious MDS needs no client-side auth (PR:N/AV:N/AC:L); OOB read yields kernel memory disclosure (C:H) and crashes (A:H) but no direct write, so I:N.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE 8.2 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Red Hat 7.0 HIGH

Primary rating from Vendor (Linux).

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

4
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
UNKNOWN (no severity yet)
CVE Published
Aug 10, 2026 - 11:59 cve.org
CRITICAL 9.8

DescriptionCVE.org

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

ceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()

ceph_handle_caps() reads snap_trace_len from the wire-format ceph_mds_caps header and uses it unconditionally to build a fake end pointer (snaptrace + snaptrace_len) that is later handed to ceph_update_snap_trace() in the CEPH_CAP_OP_IMPORT case:

snaptrace = h + 1; snaptrace_len = le32_to_cpu(h->snap_trace_len); p = snaptrace + snaptrace_len; ... case CEPH_CAP_OP_IMPORT: if (snaptrace_len) { ... if (ceph_update_snap_trace(mdsc, snaptrace, snaptrace + snaptrace_len, false, &realm)) { ... }

ceph_update_snap_trace() then decodes a struct ceph_mds_snap_realm from snaptrace using ceph_decode_need(&p, e, sizeof(*ri), bad) with the attacker-supplied fake end e snaptrace + snaptrace_len. With snaptrace_len 0xFFFFFFFF the bound check is trivially satisfied, ri = p reads sizeof(struct ceph_mds_snap_realm) past the legitimate msg->front buffer, and ri->num_snaps / ri->num_prior_parent_snaps then drive further out-of-bounds reads of the encoded snap arrays.

The eleven msg_version >= 2 .. msg_version >= 12 decoder blocks above the op switch each catch this OOB through their ceph_decode_*_safe() / ceph_decode_need() helpers, but they sit behind a hdr.version-gated if, so a malicious or compromised MDS that sets msg->hdr.version = 1 reaches the IMPORT path with no version-gated decoder having validated snap_trace_len. The shape has been present since ceph_handle_caps() was introduced.

Validate snap_trace_len against the message front buffer before consuming it, using the canonical ceph_decode_need() / ceph_has_room() helper. The helper bounds the length with subtraction (n <= end - p, guarded by end >= p) rather than pointer addition, so it is wrap-safe for the attacker-controlled u32 length on 32-bit builds where p + snap_trace_len could overflow the address space. This matches the rest of the ceph decode path (e.g. the pool_ns_len check a few lines below), and the existing goto bad cleanup already covers this exit path.

Executive ViewAI

Why It Matters

A critical kernel vulnerability in Linux CephFS client enables unauthorized memory disclosure from a compromised Ceph metadata server, potentially exposing encryption keys and sensitive credentials stored in kernel memory. Organizations using Ceph for distributed storage face data exposure risk if metadata infrastructure is infiltrated or compromised. Remediation requires patching all affected Linux systems.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.2%
Top 88% exploitable
Prevalence
Medium
Linux kernel is ubiquitous but the CephFS client runs only on hosts mounting CephFS
Threat Intel
1
1 sources
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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Vendor StatusVendor

SUSE

Severity: Important
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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