Vulnerability in The Tcpdump Group Libpcap

CVE-2026-18238

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (7.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-18238: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-18238?
CVE-2026-18238 is a medium-severity vulnerability in The Tcpdump Group Libpcap, classified under Buffer Over-read. CVSS score: 5.0/10. Published 2026-09-05.
How severe is CVE-2026-18238?
Medium severity. CVSS v3 base score is 5.0 out of 10.