CVE-2026-31478
Linux Kernel vulnerability
- Published22 Apr 2026
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/0e55f63dd08f09651d39e1b709a91705a8a0ddcb
- https://git.kernel.org/stable/c/4cb537ae4f37d7d0f617815ed4bed7173fb50861
- https://git.kernel.org/stable/c/6aef1765d6807e0f027cd87f6ac973eb0879a46d
- https://git.kernel.org/stable/c/70b4c414889492c522b6e4331562360f49be2361
- https://git.kernel.org/stable/c/80824c7e527b70cf9039534e60aff592e8f209d1
- https://git.kernel.org/stable/c/9a7166f0ef8cbb7bb48dd05e2471d995566003f5
References
- https://git.kernel.org/stable/c/0e55f63dd08f09651d39e1b709a91705a8a0ddcb
- https://git.kernel.org/stable/c/4cb537ae4f37d7d0f617815ed4bed7173fb50861
- https://git.kernel.org/stable/c/6aef1765d6807e0f027cd87f6ac973eb0879a46d
- https://git.kernel.org/stable/c/70b4c414889492c522b6e4331562360f49be2361
- https://git.kernel.org/stable/c/80824c7e527b70cf9039534e60aff592e8f209d1
- https://git.kernel.org/stable/c/9a7166f0ef8cbb7bb48dd05e2471d995566003f5
- https://git.kernel.org/stable/c/c3a89e3ec1ccf64fa6a34e391e1581ebbcba8683
Frequently asked
Is CVE-2026-31478 being actively exploited?
CVE-2026-31478 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.74%.
How severe is CVE-2026-31478?
CVE-2026-31478 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.74% probability of exploitation.
Which products are affected by CVE-2026-31478?
Affected products include Linux Kernel.
How do I fix CVE-2026-31478?
Upgrade affected software to a fixed version, for example Linux Kernel 5.15.203 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-31478 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.