# CVE-2026-0799 — The Tcpdump Group libpcap

> As of 2026-09-05, CVE-2026-0799 is a HIGH-severity vulnerability in The Tcpdump Group libpcap, CVSS v3.1 8.7, EPSS 0.1% (1.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-0799 as of 2026-09-05; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-05

## What is CVE-2026-0799?

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.

The record classifies CVE-2026-0799 under weakness classes [CWE-129](https://cwe.mitre.org/data/definitions/129.html), [CWE-125](https://intel.threadlinqs.com/cwe/CWE-125), [CWE-787](https://intel.threadlinqs.com/cwe/CWE-787). Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction, and has high impact on integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 30 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.7 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:H`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 1.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-05

## Is CVE-2026-0799 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **The Tcpdump Group**: libpcap

## How to fix CVE-2026-0799

No vendor patch reference has been recorded for CVE-2026-0799 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-0799

No threat campaign in the Threadlinqs corpus currently references CVE-2026-0799, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-06.

**Vendor advisory and patch**

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

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-0799
Full detection coverage and IOCs for threats exploiting CVE-2026-0799 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp