CVE-2026-31677 crypto: af_alg - limit RX SG extraction by receive buffer budget
A flaw in the Linux kernel's af_alg crypto module allows attackers to cause a denial of service by exhausting receive buffer budgets.
- 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-2026-31677?
CVE-2026-31677 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 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:
crypto: af_alg - limit RX SG extraction by receive buffer budget
Make af_alg_get_rsgl() limit each RX scatterlist extraction to the remaining receive buffer budget.
af_alg_get_rsgl() currently uses af_alg_readable() only as a gate before extracting data into the RX scatterlist. Limit each extraction to the remaining af_alg_rcvbuf(sk) budget so that receive-side accounting matches the amount of data attached to the request.
If skcipher cannot obtain enough RX space for at least one chunk while more data remains to be processed, reject the recvmsg call instead of rounding the request length down to zero.
Which versions are affected by CVE-2026-31677?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31677?
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-2026-31677 being exploited?
There is no known exploitation of CVE-2026-31677 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-84210, BELL-CVE-2026-31677, DEBIAN-CVE-2026-31677, GHSA-25g2-2jj3-xvxx, ROOT-OS-DEBIAN-11-CVE-2026-31677, ROOT-OS-DEBIAN-12-CVE-2026-31677 and 3 more.