CVE-2025-40176 tls: wait for pending async decryptions if tls_strp_msg_hold fails
A use-after-free vulnerability in the Linux kernel TLS subsystem allows attackers to execute arbitrary code or escalate privileges via async decryption failures.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40176?
CVE-2025-40176 is a critical use after free vulnerability in Linux, published on 12 Nov 2025. 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:
tls: wait for pending async decryptions if tls_strp_msg_hold fails
Async decryption calls tls_strp_msg_hold to create a clone of the input skb to hold references to the memory it uses. If we fail to allocate that clone, proceeding with async decryption can lead to various issues (UAF on the skb, writing into userspace memory after the recv() call has returned).
In this case, wait for all pending decryption requests.
Which versions are affected by CVE-2025-40176?
How do I fix CVE-2025-40176?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-40176 being exploited?
There is no known exploitation of CVE-2025-40176 in the wild and no public exploit code.
Sources
Also known as AZL-70028, BELL-CVE-2025-40176, DEBIAN-CVE-2025-40176, GHSA-79rw-jwgh-qv55, ROOT-OS-DEBIAN-13-CVE-2025-40176, ROOT-OS-UBUNTU-2404-CVE-2025-40176 and 1 more.