HOMEVULNERABILITIESCVE-2026-31478
CRITICAL

CVE-2026-31478

Published: April 22, 2026· Updated: Apr 27, 2026

9.8
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:8.7th

Official Description

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()

After this commit (e2b76ab8b5c9 "ksmbd: add support for read compound"),

response buffer management was changed to use dynamic iov array.

In the new design, smb2_calc_max_out_buf_len() expects the second

argument (hdr2_len) to be the offset of ->Buffer field in the

response structure, not a hardcoded magic number.

Fix the remaining call sites to use the correct offsetof() value.

NVD Source

Technical Analysis

CVE-2026-31478 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Linux1 product
linux kernel
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://git.kernel.org/stable/c/0e55f63dd08f09651d39e1b709a91705a8a0ddcb
PATCHhttps://git.kernel.org/stable/c/4cb537ae4f37d7d0f617815ed4bed7173fb50861
PATCHhttps://git.kernel.org/stable/c/6aef1765d6807e0f027cd87f6ac973eb0879a46d
PATCHhttps://git.kernel.org/stable/c/70b4c414889492c522b6e4331562360f49be2361
PATCHhttps://git.kernel.org/stable/c/80824c7e527b70cf9039534e60aff592e8f209d1
PATCHhttps://git.kernel.org/stable/c/9a7166f0ef8cbb7bb48dd05e2471d995566003f5
PATCHhttps://git.kernel.org/stable/c/c3a89e3ec1ccf64fa6a34e391e1581ebbcba8683

All References (7)

→
https://git.kernel.org/stable/c/0e55f63dd08f09651d39e1b709a91705a8a0ddcbPatch
→
https://git.kernel.org/stable/c/4cb537ae4f37d7d0f617815ed4bed7173fb50861Patch
→
https://git.kernel.org/stable/c/6aef1765d6807e0f027cd87f6ac973eb0879a46dPatch
→
https://git.kernel.org/stable/c/70b4c414889492c522b6e4331562360f49be2361Patch
→
https://git.kernel.org/stable/c/80824c7e527b70cf9039534e60aff592e8f209d1Patch
→
https://git.kernel.org/stable/c/9a7166f0ef8cbb7bb48dd05e2471d995566003f5Patch
→
https://git.kernel.org/stable/c/c3a89e3ec1ccf64fa6a34e391e1581ebbcba8683Patch

Quick Facts

CVE IDCVE-2026-31478
CVSS Score9.8 / 10
SeverityCRITICAL
CISA KEVNo
EPSS (30d)0.03%
Affected1 vendor
PublishedApr 22, 2026

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-31478 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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