> CVE-2026-55203 [CRITICAL]

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PUBLISHED
2026-06-18 17:16
MODIFIED
2026-06-18 17:16
CVSS_SCORE V3
9.0
EPSS (Prob. Exploit)
0.33%
Top 74.3%
DATA SOURCES:
NVD đź”— 2026-06-18 CWE MITRE đź”— 2026-11-01 FIRST EPSS đź”— 2026-10-25 OSV đź”— 2026-07-26 MSRC đź”— 2026-11-02

> DESCRIPTION

HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/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

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/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
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
None (N)
Aucune divulgation d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
None
Aucune divulgation d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-190

> CWE DETAILED DESCRIPTIONS

CWE-190: Integer Overflow or Wraparound - The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions. Red Hat Product Security has rated this update as having a security impact of Important. A C...
Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions. Red Hat Product Security has rated this update as having a security impact of Important. A C...
Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 10.0 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vul...
Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 9.6 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vuln...
Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (...
Red Hat Security Advisory: haproxy security update
An update for haproxy is now available for Red Hat Enterprise Linux 10. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System...
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update
The latest release of Red Hat Update Infrastructure. For more details, see the product documentation.

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

HAProxy - Integer Overflow in FCGI Demux Record Length Field

AFFECTED PACKAGES:
Unknown / Unknown
384 versions affected
ALIASES:
BIT-haproxy-2026-55203

> HISTORIQUE DES MODIFICATIONS

Première apparition
18/06/2026 17:16
Source: NVD
đź“Š ENRICHISSEMENT 01/07/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-190: Integer Overflow or Wraparound - The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will a...
Total des modifications: 1 Dernière mise à jour: 4 months ago

> REFERENCES

https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6...
https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-reco...
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