> CVE-2026-93990 [HIGH]

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PUBLISHED
2026-09-19 23:17
MODIFIED
2026-09-19 23:17
CVSS_SCORE V3
8.7
EPSS (Prob. Exploit)
0.40%
Top 67.0%
DATA SOURCES:
NVD đź”— 2026-09-20 CWE MITRE đź”— 2026-10-01 FIRST EPSS đź”— 2026-10-19 OSV đź”— 2026-10-19 MSRC đź”— 2026-09-23

> DESCRIPTION

Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.

> 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:N/PR:N/UI:N/VC:N/VI:H/VA:N/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

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/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
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-176

> CWE DETAILED DESCRIPTIONS

CWE-176: Improper Handling of Unicode Encoding - The product does not properly handle when an input contains Unicode encoding.

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
An update for Red Hat Hardened Images RPMs is now available.
Red Hat Security Advisory: expat security update
An update for expat is now available for Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CV...
Red Hat Security Advisory: expat security update
An update for expat 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 (CV...
Red Hat Security Advisory: expat security update
An update for expat 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 (C...
Red Hat Security Advisory: Red Hat Cost Management On-Premise container image update
Updated container image for Red Hat Cost Management On-Premise is now available.
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)

Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate

AFFECTED PACKAGES:
Unknown / Unknown
71 versions affected

> HISTORIQUE DES MODIFICATIONS

Première apparition
19/09/2026 23:17
Source: NVD
đź“Š ENRICHISSEMENT 01/10/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-176: Improper Handling of Unicode Encoding - The product does not properly handle when an input contains Unicode encoding.
Total des modifications: 1 Dernière mise à jour: 3 weeks ago

> REFERENCES

https://github.com/libexpat/libexpat
https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342...
https://github.com/libexpat/libexpat/pull/1282
https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-accept...
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