CVE-2026-55392

NILFS utilities - Undefined Behavior and Out-of-Memory via Unvalidated s_log_block_size

MEDIUM
5.5
CVSS Score
Published: June 18, 2026 at 06:00 PM UTC
Updated: October 26, 2026 at 11:10 AM UTC
1 product affected across 1 vendorNilfs Utils

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 2.3.0
Vendor states this is fixed in 26efb5daff0757365101035145331b0a5a85d9d9 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.5MEDIUMVulnCheck
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-1284

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