# CVE-2026-0799: libpcap BPF interpreter scratch memory validation bypass

Source: https://junglewise.ai/threats/cve-2026-0799-libpcap-bpf-interpreter-scratch-memory-validation-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-05. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-0799 · Severity: high · CVSS 8.7 · Published 2026-09-05

libpcap is a packet capture library used by network analysis tools like Wireshark and tcpdump. A vulnerability in its BPF (Berkeley Packet Filter) interpreter allows a crafted filter program to read and write arbitrary memory locations in the host process, potentially exposing sensitive data, corrupting memory, or triggering denial-of-service crashes.

Technologies: [Tcpdump.Org Libpcap](https://junglewise.ai/threats/technologies/libpcap). Vendors: [Tcpdump.Org](https://junglewise.ai/threats/vendors/tcpdump-org).

## Quick answers

**Is CVE-2026-0799 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-0799 being exploited in the wild.

**How severe is CVE-2026-0799?** High severity, with a CVSS score of 8.7, published 5 September 2026.

**Which products and versions are affected?** tcpdump.org libpcap.

**Is there a fix for CVE-2026-0799?** A patch was published on 2026-09-05: Fix applied in commit 48e8960 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-0799 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-0799?** 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 BPF interpreter in libpcap fails to validate register indices in load/store instructions that access scratch memory (M[] array). The register index must be an unsigned 32-bit integer not exceeding 15, but the interpreter does not enforce this constraint. An attacker providing a malicious BPF filter via pcap_offline_filter() or the deprecated bpf_filter() function can trigger out-of-bounds memory access, reading and writing arbitrary process memory starting at the current stack frame on 64-bit systems (up to 16 GiB) or throughout the entire address space on 32-bit systems. This can result in stack buffer overflow, information disclosure, or process crash (SIGSEGV/SIGBUS). The fix validates the index and rejects packets when an invalid index is encountered.

## Affected products

- tcpdump.org libpcap

## Timeline

- 2026-09-05: disclosed: CVE-2026-0799 published
- 2026-09-05: patched: Fix applied in commit 48e8960

## References

- [https://github.com/the-tcpdump-group/libpcap/commit/48e8960a7108e9e828f9d7bdc7e97bdab841aec7](https://github.com/the-tcpdump-group/libpcap/commit/48e8960a7108e9e828f9d7bdc7e97bdab841aec7)

## Related threats

- [libpcap BPF interpreter infinite loop in ja instruction](https://junglewise.ai/threats/cve-2026-6554-libpcap-bpf-interpreter-infinite-loop-in-ja-instruction)
- [libpcap BPF interpreter buffer bounds check bypass](https://junglewise.ai/threats/cve-2026-31912-libpcap-bpf-interpreter-buffer-bounds-check-bypass)
- [libpcap BPF interpreter abort on invalid opcode](https://junglewise.ai/threats/cve-2026-31911-libpcap-bpf-interpreter-abort-on-invalid-opcode)
- [libpcap RPCAP message validation buffer over-read](https://junglewise.ai/threats/cve-2026-18238-libpcap-rpcap-message-validation-buffer-over-read)