CVE-2026-31705: Linux kernel · ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 11 Nov 2026, 23:24 UTC
Contested
Critical score, yet low EPSS after six months · One scorer or none| CNA (Linux) | CVSS 3.1 | 9.8 |
|---|
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Linux Linux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space. When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory. Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes. This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.
References
- git.kernel.org/stable/c/ddbbc8b2a09dd2cfed90871313e3691ae1db08a2 (opens in a new tab)
- git.kernel.org/stable/c/ffbce350c6fd1e99116ea57383b9031717e36d3b (opens in a new tab)
- git.kernel.org/stable/c/98f3de6ef4efbd899348d333f0902dc4ff14380c (opens in a new tab)
- git.kernel.org/stable/c/790304c02bf9bd7b8171feda4294d6e62d32ae8f (opens in a new tab)
- git.kernel.org/stable/c/922d48fe8c19f388ffa2f709f33acaae4e408de2 (opens in a new tab)
- git.kernel.org/stable/c/30010c952077a1c89ecdd71fc4d574c75a8f5617 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)