CVE-2026-10645

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 directory block is read into a block_size-sized slab buffer, and block_off can be driven near the block end by preceding entries' rec_len, so the 8-byte header read and the subsequent name memcpy can read up to ~263 bytes past the end of the block buffer into adjacent heap/slab memory. On the readdir path those bytes are returned to the caller in fs_dirent.name, leaking adjacent kernel heap memory; a de_rec_len of 0 also causes a zero-progress infinite loop (denial of service), and the unlink path's memmove(de, next, next_reclen) over unvalidated records is an additional OOB read/write source. The defect is reached by any path-based operation (open, stat, unlink, rename, mkdir) or directory listing on a mounted ext2 volume, so a crafted or corrupted ext2 image on attacker-supplied storage (SD card, USB mass storage, or otherwise mounted image) triggers it. Affected: Zephyr ext2 from its introduction in v3.5.0 through v4.4.0. The fix validates rec_len and name_len in the parser and rejects entries whose header does not fit the remaining block or whose rec_len crosses the block boundary in every traversal caller.

CVSS v3 4.9 MEDIUM

4.9^/10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 0.7 / Impact : 4.2

Attack Vector PHYSICAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/zephyrproject-rtos/zephyr/commit/7cdb534a3c3daeaec18f656953857dcafa33a2bf
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hwrh-9h3x-vccm	Exploit Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:*

History

14 Jul 2026, 19:16

Type	Values Removed	Values Added
Summary	(en) Zephyr's ext2 directory-entry parser does not fully validate on-disk directory entry structure before copying the entry name and advancing traversal state. In ext2_fetch_direntry() (subsys/fs/ext2/ext2_diskops.c), the code only checks de_name_len <= EXT2_MAX_FILE_NAME and then copies the name with memcpy without validating the structural relationship between de_rec_len, de_name_len, and the directory block boundary (for example that de_rec_len is non-zero, at least the size of the entry header, and that the record fits within the block). Callers such as find_dir_entry() and ext2_get_direntry() (subsys/fs/ext2/ext2_impl.c) then advance traversal using the unvalidated de_rec_len. A crafted ext2 image can therefore cause an out-of-bounds read from the directory block buffer when a malformed entry near the end of a block triggers an oversized name copy, or a zero-progress infinite loop when de_rec_len == 0. The issue is not reached at mount time but later through directory traversal paths such as pathname lookup, stat/open/unlink/rename, and readdir. The primary impact is denial of service and out-of-bounds reads under attacker-controlled ext2 images mounted from untrusted media.	(en) 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 directory block is read into a block_size-sized slab buffer, and block_off can be driven near the block end by preceding entries' rec_len, so the 8-byte header read and the subsequent name memcpy can read up to ~263 bytes past the end of the block buffer into adjacent heap/slab memory. On the readdir path those bytes are returned to the caller in fs_dirent.name, leaking adjacent kernel heap memory; a de_rec_len of 0 also causes a zero-progress infinite loop (denial of service), and the unlink path's memmove(de, next, next_reclen) over unvalidated records is an additional OOB read/write source. The defect is reached by any path-based operation (open, stat, unlink, rename, mkdir) or directory listing on a mounted ext2 volume, so a crafted or corrupted ext2 image on attacker-supplied storage (SD card, USB mass storage, or otherwise mounted image) triggers it. Affected: Zephyr ext2 from its introduction in v3.5.0 through v4.4.0. The fix validates rec_len and name_len in the parser and rejects entries whose header does not fit the remaining block or whose rec_len crosses the block boundary in every traversal caller.
References		() https://github.com/zephyrproject-rtos/zephyr/commit/7cdb534a3c3daeaec18f656953857dcafa33a2bf -

06 Jul 2026, 19:39

Type	Values Removed	Values Added
CPE		cpe:2.3:o:zephyrproject:zephyr::::::::
References	~~() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hwrh-9h3x-vccm -~~	() https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hwrh-9h3x-vccm - Exploit, Patch, Vendor Advisory
First Time		Zephyrproject zephyr Zephyrproject

23 Jun 2026, 01:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-23 01:16

Updated : 2026-07-14 19:16

NVD link : CVE-2026-10645

Mitre link : CVE-2026-10645

CVE.ORG link : CVE-2026-10645

JSON object : View

Products Affected

zephyrproject

zephyr

CWE

CWE-125

Out-of-bounds Read

4.9 /10