CVE-2026-98318 smb: client: validate absolute native symlink targets before NT fixups
A user with write access to a mounted SMB share can trigger buffer overflows and integer underflows in the Linux kernel SMB client, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98318?
CVE-2026-98318 is a high-severity memory corruption vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: validate absolute native symlink targets before NT fixups
With symlinkroot unset, an absolute target is copied without conversion to an NT drive path. Later code still assumes an NT prefix is present when modifying the target and calculating the print name length.
For "/ab", this causes two failures: sym[5] and path[5] are written past their allocations, and plen -= 2 * poff subtracts an assumed 8-byte prefix from a 6-byte UTF-16 target, wrapping u16 plen to 65534. That underflow causes another overflow: memcpy() copies 65534 bytes into a 24-byte buffer. A user with write access to a mounted share can trigger these bugs with default settings.
Validate the NT drive prefix, including an ASCII drive letter, before accessing fixed offsets or subtracting the prefix length.
Which versions are affected by CVE-2026-98318?
How do I fix CVE-2026-98318?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-98318 being exploited?
There is no known exploitation of CVE-2026-98318 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98318, DEBIAN-CVE-2026-98318, GHSA-fp2w-r96h-w2cp, UBUNTU-CVE-2026-98318.