CVE-2026-13478

Device crash via oversized ext2 block count

Published Aug 25, 2026 · Updated Aug 25, 2026

Out-of-bounds read in Zephyr RTOS 3.5.0 through 4.4.1 allows attackers to crash devices via a crafted ext2 image. During mount, ext2_init_fs() passes an unbounded superblock-derived block count to ext2_bitmap_count_set(), which scans beyond its one-block bitmap buffer. Exposure requires ext2 support and a workflow that mounts attacker-controlled media or images; the over-read faults and crashes the device without returning adjacent memory.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Zephyr RTOS 3.5.0 through 4.4.1 allows attackers to crash devices via a crafted ext2 image. During mount, ext2_init_fs() passes an unbounded superblock-derived block count to ext2_bitmap_count_set(), which scans beyond its one-block bitmap buffer. Exposure requires ext2 support and a workflow that mounts attacker-controlled media or images; the over-read faults and crashes the device without returning adjacent memory.

The record

CVE
CVE-2026-13478
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-125, T1499
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 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=3.5.0 <4.4.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Zephyr Project · Zephyr RTOSversion=3.5.0 <4.4.2

Published CVSS scores

5.5Zephyr ProjectCVSS:3.1/AV:L/AC:L/PR:L/UI:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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