CVE-2026-31518 esp: fix skb leak with espintcp and async crypto
A memory leak in the Linux kernel's ESP over TCP implementation with async crypto can lead to resource exhaustion and denial of service.
- 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-2026-31518?
CVE-2026-31518 is a medium-severity denial of service vulnerability in Linux kernel, published on 22 Apr 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:
esp: fix skb leak with espintcp and async crypto
When the TX queue for espintcp is full, esp_output_tail_tcp will return an error and not free the skb, because with synchronous crypto, the common xfrm output code will drop the packet for us.
With async crypto (esp_output_done), we need to drop the skb when esp_output_tail_tcp returns an error.
Weakness: CWE-401
Which versions are affected by CVE-2026-31518?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31518?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-31518 being exploited?
There is no known exploitation of CVE-2026-31518 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83279, BELL-CVE-2026-31518, DEBIAN-CVE-2026-31518, GHSA-f37v-5r8j-33m9, ROOT-OS-DEBIAN-11-CVE-2026-31518, ROOT-OS-DEBIAN-12-CVE-2026-31518 and 4 more.