CVE-2026-55392

Tool crashes via unchecked superblock block-size shifts

Published Jun 18, 2026 · Updated Jun 18, 2026

Improper input validation in NILFS Development nilfs-utils 2.3.0 and earlier allows attackers to crash tools via a crafted image. The nilfs_sb_is_valid() routine accepts s_log_block_size values above 6, after which shifts and allocations use the oversized value and cause undefined behavior or memory exhaustion. Exploitation requires an affected utility to process a crafted NILFS2 image, and the reported consequence is limited to crashing that tool.

CVSS severity6.7
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in NILFS Development nilfs-utils 2.3.0 and earlier allows attackers to crash tools via a crafted image. The nilfs_sb_is_valid() routine accepts s_log_block_size values above 6, after which shifts and allocations use the oversized value and cause undefined behavior or memory exhaustion. Exploitation requires an affected utility to process a crafted NILFS2 image, and the reported consequence is limited to crashing that tool.

The record

CVE
CVE-2026-55392
Published
Jun 18, 2026
Updated
Jun 18, 2026
Vendor
NILFS Development
Product
nilfs-utils
Classifications
CWE-1284, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=2.3.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

NILFS Development · nilfs-utilsversion=0 <=2.3.0

Published CVSS scores

6.7VulnCheckCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5VulnCheckCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1284Improper Validation of Specified Quantity in Input
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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