CVE-2026-6554 infinte loop in libpcap before 1.10.7
A crafted BPF filter program can cause an infinite loop in the libpcap interpreter, leading to a 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-2026-6554?
CVE-2026-6554 is a high-severity denial of service vulnerability in The Tcpdump Group libpcap, published on 5 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
libpcap BPF interpreter treats the offset in the 'ja L' BPF instruction as a signed integer to implement looping via backward jumps, but it does not limit the number of loop iterations. A crafted filter program or the 'protochain' primitive used on a crafted network packet can cause the interpreter to loop infinitely.
Weakness: CWE-835
Which versions are affected by CVE-2026-6554?
How do I fix CVE-2026-6554?
Upgrade to a fixed version.
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-2026-6554 being exploited?
There is no known exploitation of CVE-2026-6554 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-6554, AZL-99747, AZL-99924, BELL-CVE-2026-6554, DEBIAN-CVE-2026-6554, ECHO-7550-c016-c10c and 2 more.