CVE-2026-31478 ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
Incorrect buffer length calculation in ksmbd can lead to memory corruption, potentially allowing remote attackers to cause denial of service or execute code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31478?
CVE-2026-31478 is a critical vulnerability in Linux kernel, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-131
Which versions are affected by CVE-2026-31478?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31478?
Apply the vendor's patch.
Is CVE-2026-31478 being exploited?
There is no known exploitation of CVE-2026-31478 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31478, DEBIAN-CVE-2026-31478, GHSA-hjcf-h98x-x745, ROOT-OS-DEBIAN-12-CVE-2026-31478, ROOT-OS-UBUNTU-2204-CVE-2026-31478, ROOT-OS-UBUNTU-2404-CVE-2026-31478 and 1 more.