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Linux Kernel CVE-2026-74350

| EUVDEUVD-2026-59497 CRITICAL
2026-08-15 Linux GHSA-c2hj-4vhc-jh3m
Critical
Disputed · 9.8 Vendor: Linux
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Attack ChainAIDerived

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

  1. Access
    Craft malicious ocfs2 image with corrupt fast-symlink dinode
  2. Delivery
    Mount volume on target (device/loopback/automount)
  3. Exploit
    readlink() reads fast symlink
  4. Execution
    Unvalidated i_size drives over-read in ocfs2_fast_symlink_read_folio
  5. Impact
    Leak adjacent kernel memory or crash

Vulnerability Assessment

Exploitation Conditions

Exploitation requires that the system mount an attacker-crafted or corrupted ocfs2 filesystem containing a zero-cluster (fast) symlink dinode whose i_size exceeds the inline fast-symlink capacity or whose inline payload is not NUL-terminated exactly at i_size, and then that a fast symlink on that volume be read (e.g. via readlink/VFS page_get_link). Limiting factors: the ocfs2 module must be present/loaded, the target must actually mount the malicious volume (normally requiring mount privileges/CAP_SYS_ADMIN or an automount configuration), and the payload is triggered on the fast-symlink read path - this is not remotely reachable over a network despite the feed's AV:N rating.

Impact

The feed's CVSS 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) materially overstates real-world risk and conflicts with the description: this is not a network-reachable, unauthenticated RCE - it is a local, on-disk-metadata bug that requires mounting a crafted or corrupted ocfs2 image, so the true attack vector is Local and privileges to mount are typically needed. The impact is memory disclosure (a kernel over-read, consistent with the 'Information Disclosure' tag), not integrity or code execution, making C:H/I:H/A:H an overestimate - a kernel-memory leak plus possible crash is the realistic outcome. Corroborating low-urgency signals: EPSS 0.15% (5th percentile), no CISA KEV listing, and no public exploit - only a KASAN reproducer typical of fuzzing. Verify the vector with the vendor: CVSS says network but the description clearly implies local access via a malicious filesystem. Net priority is low-to-moderate; the population that should act quickly is the subset actually running ocfs2 (clustered/Oracle-style storage), and for those operators mounting untrusted or attacker-supplied volumes it is a genuine defense-in-depth patch rather than an emergency.

Exploit ScenarioDerived

An attacker who can present a filesystem image to a target - e.g. a crafted ocfs2 volume on a USB device, loopback image, or attacker-controlled shared LUN - mounts it (or induces automount) and issues a readlink() on a fast symlink whose dinode has a bogus i_size or missing NUL. The read path over-copies past the inode block buffer, leaking adjacent kernel memory back through readlink or crashing the kernel. Only a KASAN reproducer is known; no weaponized public exploit is identified.

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

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AnalysisAIv1 – Aug 17, 2026

Out-of-bounds kernel memory read in the Linux kernel's ocfs2 filesystem allows disclosure of adjacent kernel data when a maliciously crafted or corrupted ocfs2 volume is mounted and a fast symlink is read. ocfs2_validate_inode_block() failed to validate zero-cluster (fast) symlink dinodes, so ocfs2_fast_symlink_read_folio() would strnlen()/memcpy an inline payload whose i_size exceeds the inline area or lacks a terminating NUL, copying past the inode block buffer (KASAN flagged a 3905-byte over-read via readlink). No public exploit identified at time of analysis; EPSS is low at 0.15% (5th percentile) and the issue is not in CISA KEV.

RemediationAI

Upstream fix available via stable commits e234973f286ed2e8961a24561ec91594ec3e3ff8 and f9e2cb692b77a679b1f4cc2b7b277fa908586533 (https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8 and https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533); update to a kernel containing these - the 7.1.5 stable release or 7.2-rc1 and later - which adds validation of fast-symlink dinodes in ocfs2_validate_inode_block(). If you cannot patch immediately, the most effective compensating control is to avoid mounting untrusted ocfs2 images: blacklist/unload the ocfs2 module on hosts that do not need it (modprobe -r ocfs2 / install ocfs2 /bin/true), which eliminates exposure entirely but breaks any legitimate ocfs2 use; and restrict who can mount filesystems by disabling automount of removable media and ensuring only privileged, trusted administrators can attach ocfs2 volumes, at the cost of reduced convenience for removable-storage workflows.

Affected VersionsENISA

Linux patch: 0
Linux 3.5
Linux patch: 7.1.5
Linux ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1 <e234973f286ed2e8961a24561ec91594ec3e3ff8
Linux ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1 <f9e2cb692b77a679b1f4cc2b7b277fa908586533
Linux patch: 7.2-rc1

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

ocfs2 is Oracle Cluster File System v2, a shared-disk clustered filesystem in the mainline Linux kernel (fs/ocfs2). A 'fast symlink' stores its target inline within the inode (dinode) block when the symlink occupies zero data clusters, and is later resolved through the VFS page_get_link() path via ocfs2_fast_symlink_read_folio(). The root cause is a missing input-validation/bounds check (CWE-125 Out-of-bounds Read class; CWE listed as N/A in the feed) on untrusted on-disk metadata: the read path trusts i_size and assumes NUL-termination, so a dinode claiming an i_size larger than the inline fast-symlink capacity, or without a NUL at i_size, drives strnlen()/memcpy beyond the block buffer. The CPE data identifies the affected product only generically as cpe:2.3:a:linux:linux, i.e. the Linux kernel itself; the practical exposure is confined to systems that mount ocfs2 volumes.

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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 6.1 MEDIUM

Requires mounting a crafted ocfs2 volume (AV:L, PR:L for mount capability); over-read leaks kernel memory (C:H) with possible crash (A:L) and no integrity impact (I:N).

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N
SUSE 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat 5.5 MEDIUM

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

3
CVSS changed
Aug 17, 2026 - 06:22 NVD
9.8 (CRITICAL)
CVE Published
Aug 15, 2026 - 05:58 cve.org
CRITICAL 9.8
CVE Published
Aug 15, 2026 - 05:58 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

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

ocfs2: validate fast symlink target during inode read

ocfs2_validate_inode_block() already rejects several inconsistent self-contained dinodes before they are exposed to the rest of the filesystem. Fast symlinks need the same treatment.

A zero-cluster symlink is treated as a fast symlink and later read through page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses strnlen() on the inline payload and then copies len + 1 bytes into the folio. If a corrupt dinode stores an i_size that does not fit the inline area or omits the terminating NUL at i_size, that copy reads past the end of the inode block buffer.

Reject zero-cluster symlink dinodes whose i_size exceeds the inline fast-symlink capacity or whose inline payload is not NUL-terminated exactly at i_size when the inode block is validated. This keeps malformed fast symlinks from reaching the read path.

Validation reproduced this kernel report: KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0 RIP: 0033:0x7f5c6d859aa7 Read of size 3905 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xce/0x630 (?:?) ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x19f/0x330 (?:?) kasan_report+0xe0/0x110 (?:?) kasan_check_range+0x105/0x1b0 (?:?) __asan_memcpy+0x23/0x60 (?:?) filemap_read_folio+0x27/0xe0 (?:?) filemap_read_folio+0x35/0xe0 (?:?) do_read_cache_folio+0x138/0x230 (?:?) __page_get_link+0x26/0x110 (?:?) page_get_link+0x2e/0x70 (?:?) vfs_readlink+0x15e/0x250 (?:?) touch_atime+0x4d/0x370 (?:?) do_readlinkat+0x186/0x200 (?:?) do_user_addr_fault+0x65a/0x890 (?:?) __x64_sys_readlink+0x46/0x60 (?:?) do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)

Executive ViewAI

Why It Matters

A critical out-of-bounds memory read in the Linux kernel's ocfs2 filesystem (CVE-2026-74350) can disclose adjacent kernel data when maliciously crafted volumes are mounted and symlinks are read. Organizations using Oracle Cluster File System face risk of kernel memory leakage, which could support privilege escalation or further kernel exploitation; however, EPSS is low (0.2%) and no active exploitation has been identified.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: restrict ocfs2 volume sources to internally-controlled media; enforce strict RBAC on mount permissions; disable ocfs2 support on systems that do not require it; monitor kernel logs for KASAN memory warnings; apply kernel hardening (SELinux or AppArmor) to restrict filesystem access paths; maintain updated inventory of ocfs2 deployments and volume sources.

Threat Intelligence Overview

EPSS Score
0.2%
Top 95% exploitable
Prevalence
Low
ocfs2 is a niche clustered filesystem, rarely enabled in typical deployments
Data Quality
5 sources
Confidence: Medium

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

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

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 16.0 Not-Affected

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