CVE-2026-53004 sctp: fix OOB write to userspace in sctp_getsockopt_peer_auth_chunks
An out-of-bounds write in the Linux kernel SCTP module allows an unprivileged local user to corrupt adjacent userspace memory via a crafted getsockopt call.
- 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-2026-53004?
CVE-2026-53004 is a high-severity memory corruption vulnerability in Linux kernel, published on 24 Jun 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:
sctp: fix OOB write to userspace in sctp_getsockopt_peer_auth_chunks
sctp_getsockopt_peer_auth_chunks() checks that the caller's optval buffer is large enough for the peer AUTH chunk list with
if (len < num_chunks) return -EINVAL;
but then writes num_chunks bytes to p->gauth_chunks, which lives at offset offsetof(struct sctp_authchunks, gauth_chunks) == 8 inside optval. The check is missing the sizeof(struct sctp_authchunks) = 8-byte header. When the caller supplies len == num_chunks (for any num_chunks > 0) the test passes but copy_to_user() writes sizeof(struct sctp_authchunks) = 8 bytes past the declared buffer.
The sibling function sctp_getsockopt_local_auth_chunks() at the next line already has the correct check:
if (len < sizeof(struct sctp_authchunks) + num_chunks) return -EINVAL;
Align the peer variant with its sibling.
Reproducer confirms on v7.0-13-generic: an unprivileged userspace caller that opens a loopback SCTP association with AUTH enabled, queries num_chunks with a short optval, then issues the real getsockopt with len == num_chunks and sentinel bytes painted past the buffer observes those sentinel bytes overwritten with the peer's AUTH chunk type. The bytes written are under the peer's control but land in the caller's own userspace; this is not a kernel memory corruption, but it is a kernel-side contract violation that can silently corrupt adjacent userspace data.
Weakness: CWE-787
Which versions are affected by CVE-2026-53004?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53004?
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-2026-53004 being exploited?
There is no known exploitation of CVE-2026-53004 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53004, DEBIAN-CVE-2026-53004, GHSA-79rv-wg4r-99gp, ROOT-OS-DEBIAN-11-CVE-2026-53004, ROOT-OS-DEBIAN-12-CVE-2026-53004, ROOT-OS-UBUNTU-2204-CVE-2026-53004 and 2 more.