CVE-2026-10645: The Zephyr ext2 filesystem driver (subsys/fs/ext2) trusted the on-disk directory entry fields de_rec_len and d

Q: How do I fix CVE-2026-10645?

zephyr: upgrade to newer than 4.4.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-10645 being exploited?

CVE-2026-10645 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-10645 affect?

CVE-2026-10645 affects zephyr. Severity is medium (CVSS 4.9). The Zephyr ext2 filesystem driver (subsys/fs/ext2) trusted the on-disk directory entry fields de_rec_len and de_name_len when walking a directory block. ext2_fetch_direntry() guarded only with de_name_len > EXT2_MAX_FILE_NAME, but de_name_l

Routine

MEDIUM 4.9UPGRADE

CVE-2026-10645 is a medium-severity flaw (CVSS 4.9) affecting zephyr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Zephyr ext2 filesystem driver (subsys/fs/ext2) trusted the on-disk directory entry fields de_rec_len and de_name_len when walking a directory block. ext2_fetch_direntry() guarded only with de_name_len > EXT2_MAX_FILE_NAME, but de_name_len is a uint8_t and EXT2_MAX_FILE_NAME is 255, so the check is always false; the function then memcpy'd up to 255 name bytes and the lookup/readdir paths advanced traversal by an unvalidated de_rec_len. Each di

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.9 (Medium)
Attack vector	Physical
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 95%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-06-23
Last modified	2026-10-25

Publisher (CNA): Zephyr Project · Vendor: zephyrproject

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-23 01:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

zephyrproject zephyr UPGRADE

Affected: <= 4.4.1

Fixed in: newer than 4.4.1

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-10645?

zephyr: upgrade to newer than 4.4.1. Exact commands for each OS are on this page.

Is CVE-2026-10645 being exploited?

CVE-2026-10645 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-10645 affect?

CVE-2026-10645 affects zephyr. Severity is medium (CVSS 4.9). The Zephyr ext2 filesystem driver (subsys/fs/ext2) trusted the on-disk directory entry fields de_rec_len and de_name_len when walking a directory block. ext2_fetch_direntry() guarded only with de_name_len > EXT2_MAX_FILE_NAME, but de_name_l

How urgent is CVE-2026-10645?

Priority 23/100. Public exploit reference

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References

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