# CVE-2026-55204

## Summary

- **CVE ID:** CVE-2026-55204
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-476
- **Published:** Jun 18, 2026
- **Last Modified:** Jul 14, 2026

## Description

HAProxy through  3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.

## Affected Products

- haproxy — haproxy (0)
- haproxy — haproxy (9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513)

## References

- [CNA](https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513)
- [CNA](https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.48%
- **EPSS Percentile:** 40.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._