CVE-2026-0799: the tcpdump group libpcap Out-of-bounds Read

Vulnerability summary

CVE-2026-0799 is a high (CVSS 8.7) Out-of-bounds Read vulnerability in the tcpdump group libpcap. EPSS estimates a 0.11% chance of exploitation in the next 30 days, higher than 1.1% of scored vulnerabilities.

Timeline

1. 05-09-2026
   PublishedVulnerability first disclosed.
2. 08-09-2026
   Last modifiedVulnerability information updated.

Description

In BPF instructions that load/store a value from/to a scratch memory register the register index is an unsigned 32-bit integer and must not exceed 15, but libpcap BPF interpreter does not validate the value. In particular uncommon use cases a crafted filter program can cause the interpreter to try reading and writing the OS process memory in the 16GiB starting at the current stack frame on 64-bit architectures and in the entire address space on 32-bit architectures.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.
• CWE-129Improper Validation of Array IndexThe product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.