Quick answers
- Is CVE-2026-31911 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-31911 being exploited in the wild.
- How severe is CVE-2026-31911?
- Medium severity, with a CVSS score of 5.5, published 5 September 2026.
- Which products and versions are affected?
- tcpdump.org libpcap.
- Is there a fix for CVE-2026-31911?
- A patch was published on 2026-09-05: Fix implemented in commit a715bcd Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-31911 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-31911?
- Check whether you run Tcpdump.Org Libpcap. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability exists in the BPF interpreter function pcapint_filter_with_aux_data(), which calls abort() when it encounters a BPF instruction with an invalid opcode. While libpcap-generated programs are assumed to never have invalid opcodes, programs from external sources (e.g., via pcap_offline_filter() or the deprecated bpf_filter()) may contain invalid opcodes due to gaps in the validator. An attacker can supply a crafted BPF filter program to cause immediate process termination. The fix changes the interpreter to safely reject packets with invalid opcodes instead of calling abort().
Affected products
- tcpdump.org libpcap
Timeline
- 2026-09-05: disclosed
- 2026-09-05: patched: Fix implemented in commit a715bcd