CVE-2026-63912 xfrm: esp: restore combined single-frag length gate
A missing length check in the Linux kernel ESP fast path can cause memory corruption, potentially leading to denial of service or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63912?
CVE-2026-63912 is a critical memory corruption vulnerability in Linux, published on 19 Jul 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:
xfrm: esp: restore combined single-frag length gate
The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len.
Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len.
Restore this combined-length page gate for both IPv4 and IPv6.
Weakness: CWE-125
Which versions are affected by CVE-2026-63912?
How do I fix CVE-2026-63912?
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-2026-63912 being exploited?
There is no known exploitation of CVE-2026-63912 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63912, DEBIAN-CVE-2026-63912, GHSA-6c6h-95cx-j99f, ROOT-OS-UBUNTU-2204-CVE-2026-63912, UBUNTU-CVE-2026-63912.