> CVE-2026-55213 [HIGH]

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PUBLISHED
2026-07-10 21:16
MODIFIED
2026-07-10 21:16
CVSS_SCORE V3
7.5
EPSS (Prob. Exploit)
0.49%
Top 58.9%
DATA SOURCES:
NVD đź”— 2026-07-10 CWE MITRE đź”— 2026-11-01 FIRST EPSS đź”— 2026-10-25 OSV đź”— 2026-07-26

> DESCRIPTION

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1, when h2o processes a QPACK instruction sent from the peer over HTTP/3, lib/http3/qpack.c might allocate an on-stack buffer as large as approximately 800 KB by calling alloca, which exceeds the default pthread stack size used by musl libc and causes the h2o server to crash with a segmentation fault while touching the guard page. This issue is fixed in commit edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1.

> AFFECTED_PRODUCTS

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

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EXPLOITABILITY
3.9
IMPACT
3.6

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
None
Aucune divulgation d'informations
Intégrité
None
Aucune modification de données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-789

> CWE DETAILED DESCRIPTIONS

CWE-789: Memory Allocation with Excessive Size Value - The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

h2o: musl libc stack overflow (QPACK)

AFFECTED PACKAGES:
Unknown / Unknown
29 versions affected
ALIASES:
GHSA-432c-8xmj-frmq

> HISTORIQUE DES MODIFICATIONS

Première apparition
10/07/2026 21:16
Source: NVD
📊 ENRICHISSEMENT 01/08/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-789: Memory Allocation with Excessive Size Value - The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing ar...
Total des modifications: 1 Dernière mise à jour: 3 months ago

> REFERENCES

https://github.com/h2o/h2o/commit/edd7a120bfc4af11ac0cbebce2a43cc1f93f9af1
https://github.com/h2o/h2o/security/advisories/GHSA-432c-8xmj-frmq
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