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High · 7.5 CVE-2025-57632 EUVD-2025-31154GHSA-h8w6-x833-p4x4

libsmb2 6.2+ is vulnerable to Buffer Overflow. When processing SMB2 chained PDUs (NextCommand), libsmb2 repeatedly calls smb2_add_iovector(…

Published Sep 25, 2025 · Updated Jan 14, 2026 · Assigned by mitre

Description

libsmb2 6.2+ is vulnerable to Buffer Overflow. When processing SMB2 chained PDUs (NextCommand), libsmb2 repeatedly calls smb2_add_iovector() to append to a fixed-size iovec array without checking the upper bound of v->niov (SMB2_MAX_VECTORS=256). An attacker can craft responses with many chained PDUs to overflow v->niov and perform heap out-of-bounds writes, causing memory corruption, crashes, and potentially arbitrary code execution. The SMB2_OPLOCK_BREAK path bypasses message ID validation.

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 libsmb2 6.2+dfsg-3 —
Debian 13 libsmb2 6.2+dfsg-2+deb13u1 —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 libsmb2 No fix yet —
Ubuntu 26.04 LTS libsmb2 No fix yet —
Ubuntu 25.10 libsmb2 No fix yet —

References