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CVE-2026-34961 Pengutronix CVE debrief

CVE-2026-34961 is a medium-severity vulnerability in barebox, a bootloader used in embedded systems. The vulnerability is caused by missing validation of the eh_entries field against buffer capacity in fs/ext4/ext4_common.c, leading to out-of-bounds read vulnerabilities in ext4 extent parsing. An attacker can supply a malicious ext4 filesystem image via USB, SD card, or network boot to trigger heap out-of-bounds reads during boot-time filesystem parsing. This could potentially allow an attacker to access sensitive data or execute arbitrary code. Users of barebox versions prior to 2026.04.0 should be aware of this vulnerability and take steps to mitigate it.

Vendor
Pengutronix
Product
Barebox
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-11
Original CVE updated
2026-07-18
Advisory published
2026-05-11
Advisory updated
2026-07-18

Who should care

Users of barebox versions prior to 2026.04.0 should be aware of this vulnerability and take steps to mitigate it. This includes updating to version 2026.04.0 or later, and being cautious when handling ext4 filesystem images from untrusted sources. Operators, platform administrators, vulnerability management teams, and security teams should review the official advisory and CVE record to validate affected scope, severity, and vendor guidance.

Technical summary

The vulnerability is caused by a lack of validation of the eh_entries field in fs/ext4/ext4_common.c. This field is used to determine the number of extent entries in an ext4 filesystem. If an attacker can supply a malicious value for this field, they can cause the bootloader to read beyond the bounds of the filesystem image, potentially redirecting reads to arbitrary disk offsets. This could allow an attacker to access sensitive data or execute arbitrary code. The affected product is barebox, and the vulnerability is triggered during boot-time filesystem parsing.

Defensive priority

Medium

Recommended defensive actions

  • Update barebox to version 2026.04.0 or later
  • Be cautious when handling ext4 filesystem images from untrusted sources
  • Monitor for suspicious activity related to ext4 filesystem parsing
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-05-11T22:22:11.000Z and was last modified on 2026-07-18T03:16:35.290Z. The NVD entry is currently Modified. This information is based on the supplied source corpus and may not reflect the full scope of the vulnerability. Defenders should verify the affected scope and severity with the official CVE record and vendor guidance.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-05-11T22:22:11.000Z and has not been modified since then.