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.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libsmb2 | 6.2+dfsg-3 | — |
| Debian 13 | libsmb2 | 6.2+dfsg-2+deb13u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libsmb2 | No fix yet | — |
| Ubuntu 26.04 LTS | libsmb2 | No fix yet | — |
| Ubuntu 25.10 | libsmb2 | No fix yet | — |