# CVE-2026-6554 — The Tcpdump Group libpcap

> As of 2026-09-05, CVE-2026-6554 is a MEDIUM-severity vulnerability in The Tcpdump Group libpcap, CVSS v3.1 5.5, EPSS 0.0% (85.3th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-6554 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-2026-6554?

libpcap BPF interpreter treats the offset in the 'ja L' BPF instruction as a signed integer to implement looping via backward jumps, but it does not limit the number of loop iterations. In particular uncommon use cases a crafted filter program can cause the interpreter to loop infinitely.

The record classifies CVE-2026-6554 under weakness class [CWE-835](https://intel.threadlinqs.com/cwe/CWE-835). 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 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:** 5.5 — MEDIUM (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **EPSS (FIRST):** 0.0% probability of exploitation in the next 30 days, higher than 85.3% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 6.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-05

## Is CVE-2026-6554 being exploited?

It currently carries a trending score of 51 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **The Tcpdump Group**: libpcap

## How to fix CVE-2026-6554

No vendor patch reference has been recorded for CVE-2026-6554 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-2026-6554

No threat campaign in the Threadlinqs corpus currently references CVE-2026-6554, 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, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-06. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — patch](https://github.com/the-tcpdump-group/libpcap/commit/ff3c83475ac303c6b681c52ad0b6e14795a8e0ce)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-6554
Full detection coverage and IOCs for threats exploiting CVE-2026-6554 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp