Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-26717

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
25/02/2026
Last modified:
15/04/2026

Description

An issue in OpenFUN Richie (LMS) in src/richie/apps/courses/api.py. The application used the non-constant time == operator for HMAC signature verification in the sync_course_run_from_request function. This allows remote attackers to forge valid signatures and bypass authentication by measuring response time discrepancies

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 4.80 MEDIUM
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x
4.80
Severity 3.x
MEDIUM

References to Advisories, Solutions, and Tools