CVE-2026-10645
MediumCVSS 4.9Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
The Zephyr ext2 filesystem driver trusts on-disk directory entry fields de_rec_len and de_name_len when walking a directory block. The validation of de_name_len is ineffective, allowing up to 263 bytes out-of-bounds read past the block buffer, leading to kernel memory leak, and a de_rec_len of 0 causes an infinite loop (denial of service). Affected versions from v3.5.0 to v4.4.0.
Risk Assessment
The organization risks leakage of sensitive kernel memory (e.g., keys, passwords) and denial-of-service attacks by mounting a crafted ext2 image from external storage (SD card, USB mass storage).
Recommendation
Immediately update Zephyr OS to a patched version (v4.4.1 or later) or apply the fix that validates de_rec_len and de_name_len in the ext2 parser.
Other vulnerabilities in Zephyr ext2 filesystem driver
See all- CVE-2026-13478Medium
The Zephyr ext2 filesystem driver contains an out-of-bounds read vulnerability triggered when mounting a crafted ext2 image. The ext2_bitmap_count_set() function scans memory based on unvalidated superblock values, potentially reading about 512 MB past the bitmap buffer.
- CVE-2026-13215Medium
The Zephyr ext2 filesystem driver fails to validate the s_log_block_size field of the on-disk superblock when mounting a filesystem. A crafted image can cause a shift overflow or oversized block size, leading to an out-of-bounds write into static memory in kernel mode.
Original NVD description (English source)
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.