> CVE-2026-76949 [CRITICAL]

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PUBLISHED
2026-09-17 22:17
MODIFIED
2026-09-17 22:17
CVSS_SCORE V3
9.1
EPSS (Prob. Exploit)
0.77%
Top 45.2%
DATA SOURCES:
NVD đź”— 2026-09-17 CWE MITRE đź”— 2026-10-01 FIRST EPSS đź”— 2026-10-18 OSV đź”— 2026-10-19

> DESCRIPTION

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who can plant a remember-me cookie in a victim's browser to replace that victim's authenticated session with one for the attacker's own account. AshAuthentication.Plug.Helpers.sign_in_using_remember_me/3 skips re-authenticating an already-signed-in visitor by checking the session for "<subject_name>_token", but store_in_session/2 writes that key only when require_token_presence_for_authentication? is enabled and otherwise writes the bare subject name. At the default setting the guard therefore reads a key that is never written, its already-signed-in branch is unreachable, and the remember-me sign-in runs on every request through the per-request browser pipeline plug. A planted remember-me cookie is consequently honoured even for a visitor holding a live authenticated session, so whatever the victim enters afterwards lands in data the attacker controls. The read path in authenticate_resource_from_session/4 selects the key correctly, so the guard and the reader disagree about which key holds the session. This issue affects ash_authentication: from 4.10.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

> 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:H/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:P/PR:N/UI:N/VC:H/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
High (H)
Divulgation totale 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
High
Divulgation totale d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-290

> CWE DETAILED DESCRIPTIONS

CWE-290: Authentication Bypass by Spoofing - This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Remember-me sign-in guard reads a session key that is never written in ash_authentication, allowing session replacement

AFFECTED PACKAGES:
Unknown / Unknown
28 versions affected
ALIASES:
EEF-CVE-2026-76949, GHSA-hh34-374j-pfr5

> HISTORIQUE DES MODIFICATIONS

Première apparition
17/09/2026 22:17
Source: NVD
📊 ENRICHISSEMENT 01/10/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-290: Authentication Bypass by Spoofing - This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
Total des modifications: 1 Dernière mise à jour: 3 weeks ago

> REFERENCES

https://cna.erlef.org/cves/CVE-2026-76949.html
https://github.com/team-alembic/ash_authentication/commit/3d3de314692558d06ec139...
https://github.com/team-alembic/ash_authentication/commit/9a34136b844abe179da107...
https://github.com/team-alembic/ash_authentication/commit/b9568a53b438247238b1c5...
https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-hh34...
https://osv.dev/vulnerability/EEF-CVE-2026-76949
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