CVE-2026-18238 OOBR in rpcap client in libpcap before 1.10.7
A malicious RPCAP server can trigger an out-of-bounds read in libpcap, potentially leaking memory or causing a crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-18238?
CVE-2026-18238 is a medium-severity memory corruption vulnerability in The Tcpdump Group libpcap, published on 5 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The rpcap client code that processes a RPCAP_MSG_PACKET message received from the server incorrectly validates its headers. A malicious server can send a crafted message and cause the client to treat up to 20 bytes of the client process memory beyond the end of the buffer as if it was a part of the captured packet.
Which versions are affected by CVE-2026-18238?
How do I fix CVE-2026-18238?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-18238 being exploited?
There is no known exploitation of CVE-2026-18238 in the wild and no public exploit code.
Sources
Also known as AZL-99729, AZL-99927, DEBIAN-CVE-2026-18238, ECHO-bc26-fe28-c8e1, GHSA-2xr5-28gv-34j3, UBUNTU-CVE-2026-18238.