CVE-2026-43107 xfrm: account XFRMA_IF_ID in aevent size calculation
A missing size calculation for XFRMA_IF_ID in the Linux kernel xfrm subsystem can cause a kernel panic via malformed netlink interactions.
- 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-2026-43107?
CVE-2026-43107 is a medium-severity denial of service vulnerability in Linux kernel, published on 6 May 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:
xfrm: account XFRMA_IF_ID in aevent size calculation
xfrm_get_ae() allocates the reply skb with xfrm_aevent_msgsize(), then build_aevent() appends attributes including XFRMA_IF_ID when x->if_id is set.
xfrm_aevent_msgsize() does not include space for XFRMA_IF_ID. For states with if_id, build_aevent() can fail with -EMSGSIZE and hit BUG_ON(err < 0) in xfrm_get_ae(), turning a malformed netlink interaction into a kernel panic.
Account XFRMA_IF_ID in the size calculation unconditionally and replace the BUG_ON with normal error unwinding.
Weakness: CWE-131
Which versions are affected by CVE-2026-43107?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43107?
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-2026-43107 being exploited?
There is no known exploitation of CVE-2026-43107 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-85869, BELL-CVE-2026-43107, DEBIAN-CVE-2026-43107, GHSA-v6vr-f94r-r434, ROOT-OS-DEBIAN-11-CVE-2026-43107, ROOT-OS-DEBIAN-12-CVE-2026-43107 and 3 more.