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Linux Kernel ext2 EUVDEUVD-2026-76513

| CVE-2026-89601 HIGH
2026-09-11 Linux GHSA-g65m-jqm9-5xv8
High
Disputed · 8.8 Vendor: Linux
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Attack ChainAIDerived

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

  1. Access
    Mount ext2 with sync semantics
  2. Delivery
    Write metadata to IS_SYNC inode (truncate or setxattr)
  3. Exploit
    sync_inode_metadata() skips undirtied inode
  4. Execution
    Inode update silently lost
  5. Persist
    System crash or remount exposes stale on-disk metadata
  6. Impact
    Data corruption or integrity failure

Vulnerability Assessment

Exploitation Conditions

Exploitation requires: (1) an ext2 filesystem must be present and mounted with synchronous write semantics, either via the 'sync' mount option or per-file O_SYNC/IS_SYNC semantics; (2) a process must perform a file truncation (ext2_setsize) or extended attribute write (ext2_xattr_set2) on an inode that is not already marked dirty. The vulnerability is limited to ext2 - ext3/ext4 are not affected. The impact materializes only on power loss, crash, or unmount following the silent missed sync. Non-IS_SYNC (asynchronous) ext2 mounts are not affected because those take the else-branch and correctly call mark_inode_dirty().

Impact

The provided CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/C:H/I:H/A:H = 8.8) is materially overstated and inconsistent with the vulnerability. AV:N is incorrect - exploitation requires direct local filesystem interaction with an ext2 volume mounted with sync semantics; this is inherently a local operation. C:H is also unsupported - the bug causes lost writes (integrity), not information disclosure. The 'Information Disclosure' tag is similarly mislabeled. EPSS at 0.15% (5th percentile) and no KEV listing are consistent with a correctness/data-integrity defect rather than an exploitable attack path. Real-world impact is silent metadata corruption (truncated file sizes or xattr changes not persisted) on ext2 IS_SYNC mounts, which is a meaningful data-integrity risk for systems relying on synchronous durability guarantees, but requires local write access and a non-default mount configuration. This is a medium-severity correctness fix, not a critical security vulnerability.

Exploit ScenarioDerived

A process writing files or extended attributes to an ext2 filesystem mounted with the sync option silently loses those metadata updates if the inode was not previously dirty. After a system crash or clean unmount, the on-disk inode reflects stale metadata (wrong file size after truncation, or missing xattrs), leading to data corruption or application-level integrity failures. No public exploit code exists - this is a passive data-loss scenario triggered by normal filesystem operations, not an attacker-controlled code path.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 13, 2026

Silent inode metadata loss in the Linux kernel ext2 filesystem affects all systems using ext2 with IS_SYNC inodes: calls to sync_inode_metadata() in ext2_setsize() and ext2_xattr_set2() were guarded by an IS_SYNC branch that skipped mark_inode_dirty(), meaning that if the inode was not already dirty, the sync was a no-op and metadata changes were silently discarded. Affected operations include file truncation and extended attribute writes on synchronous ext2 mounts. No public exploit code exists and EPSS is 0.15%, consistent with a data-integrity correctness fix rather than a security-critical attack surface.

RemediationAI

Apply the upstream kernel patches at git.kernel.org/stable/c/5efb3350230fef831167740e69e6db2861101186 or git.kernel.org/stable/c/356984d1a5c32e94810cbb6c8dc7d8ff2d4d919a, or upgrade to Linux 7.2.4 or later (7.3-rc1 also contains the fix). As a compensating control, avoid mounting ext2 filesystems with the sync mount option or using O_SYNC on ext2 volumes on unpatched kernels - this eliminates the IS_SYNC code path entirely, though it sacrifices synchronous durability guarantees. Migrating to ext4, which has a substantially more mature and actively maintained codebase, eliminates exposure to this entire class of ext2-specific bugs. No workaround preserves both sync semantics and correct behavior on unpatched kernels.

Affected VersionsENISA

Linux patch: 7.2.4
Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <356984d1a5c32e94810cbb6c8dc7d8ff2d4d919a
Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5efb3350230fef831167740e69e6db2861101186
Linux 0 <7.2.4
Linux patch: 7.3-rc1

Affected Packages

euvd linux fix: 7.2.4

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 ext2 filesystem (second extended filesystem) is the classic Linux on-disk format, still found in embedded systems, boot partitions, and legacy deployments. IS_SYNC inodes are those mounted with synchronous write semantics (e.g., mount -o sync, or per-inode O_SYNC). The bug is a logic error: both ext2_setsize() (called on truncation) and ext2_xattr_set2() (called when setting extended attributes) used an if/else branch - if IS_SYNC, call sync_inode_metadata(inode, 1), else call mark_inode_dirty(). However, sync_inode_metadata() internally only writes the inode if it is flagged dirty. Since the inode was never dirtied before the sync call, the write was silently skipped. The fix marks the inode dirty unconditionally, then calls sync_inode_metadata(). No formal CWE is assigned, but this is best described as CWE-662 (Improper Synchronization) or CWE-754 (Improper Check for Unusual Conditions). CPE: cpe:2.3:a:linux:linux.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Sources disagree (Low–High)
Vendor (Linux) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 6.1 MEDIUM

Local filesystem operation requiring write access to ext2 IS_SYNC inode; no confidentiality impact; integrity loss is high (silent data loss), availability impact is low.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
4.0 AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
SUSE 3.3 LOW
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Red Hat 5.5 LOW

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
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
CVSS changed
Sep 13, 2026 - 07:22 NVD
8.8 (HIGH)
Patch available
Sep 11, 2026 - 21:18 EUVD
CVE Published
Sep 11, 2026 - 19:45 cve.org
UNKNOWN (no severity yet)
CVE Published
Sep 11, 2026 - 19:45 cve.org
HIGH 8.8

DescriptionCVE.org

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

ext2: Fix lost inode updates for IS_SYNC inodes

ext2_setsize() and ext2_xattr_set2() had a construct like:

if (IS_SYNC(inode)) { sync_inode_metadata(inode, 1); } else { mark_inode_dirty(inode); }

which leads to lost inode updates for IS_SYNC inodes because sync_inode_metadata() does anything only if the inode is already dirty and hence inode updates may be simply lost. Fix the problem by unconditionally marking the inode dirty and *then* call sync_inode_metadata().

Executive ViewAI

Why It Matters

Linux systems using ext2 filesystems with synchronous inodes can silently discard file metadata changes during routine file operations without error notification. Organizations with ext2-based storage-particularly in embedded, legacy, or specialized infrastructure-face undetected data corruption risk that could impact business continuity and data-protection compliance requirements.

Business Impact: Medium
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.2%
Top 95% exploitable
Prevalence
High
Linux kernel deployed on virtually all Linux systems globally
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 HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
No
Human Impact
Medium

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Vendor StatusVendor

SUSE

Severity: Low
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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