CVE-2026-72318 cifs: validate DFS referral string offsets
A malformed DFS referral in the Linux kernel CIFS module can cause out-of-bounds reads, potentially leading to denial of service or information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72318?
CVE-2026-72318 is a critical memory corruption vulnerability in Linux, published on 15 Aug 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:
cifs: validate DFS referral string offsets
parse_dfs_referrals() validates that the response header and referral array fit in the received buffer, but each referral also contains string offsets supplied by the server.
Those offsets are used to compute the DfsPath and NetworkAddress string pointers without checking whether they still point inside the response buffer. A malformed referral can therefore make the computed pointer exceed the end of the buffer. The resulting negative max_len is then passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it to kstrndup() as a size_t, allowing strnlen() to read out of bounds.
Validate each string offset before deriving the string pointer.
Which versions are affected by CVE-2026-72318?
How do I fix CVE-2026-72318?
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-2026-72318 being exploited?
There is no known exploitation of CVE-2026-72318 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72318, DEBIAN-CVE-2026-72318, GHSA-4cv4-fc78-7hch, UBUNTU-CVE-2026-72318.