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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-55204

34
FAUCET Score

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.

First published: Jun 18, 2026Last modified: Jul 14, 2026

Impacted Technologies

VendorProductVersion(s)CPE
<= 3.4.0CPE matchmatch criteria
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*
>= 0, <= 3.4.0CPE match
cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

8.7HIGH

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
HIGH
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.48%
Probability of exploitation in next 30 days
EPSS Percentile
38.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0048 is in the 17th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: azl3 haproxy 2.9.11-6 on Azure Linux 3.0Fixed in: 2.9.11-7
microsoftpatch availablevia msrc
Product: azl3 haproxy 2.9.11-7 on Azure Linux 3.0Fixed in: 2.9.11-7
microsoftpatch availablevia msrc
Product: 21468-17084Fixed in: 2.9.11-7
microsoftpatch availablevia msrc
Product: 21525-17084Fixed in: 2.9.11-7

Vendor Advisories (1)

microsoft2026-Jun/CVE-2026-55204Important

HAProxy - NULL Pointer Dereference in hpack_dht_insert Function

Jun 9, 2026

References

github.com / haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513
Patch
vulncheck.com / advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function
Third Party Advisory