---
id: CVE-2026-26717
aliases:
  - GHSA-xjhr-fm27-4hmx
  - PYSEC-2026-3052
title: >-
  OpenFUN Richie Observable Timing Discrepancy in its
  sync_course_run_from_request function
summary: >-
  OpenFUN Richie Observable Timing Discrepancy in its
  sync_course_run_from_request function
severity: medium
cvss: 4.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'
vendor: richie
product: richie
ecosystem: pip
affected:
  - richie < 3.3.0
patched:
  - richie 3.3.0
published: '2026-02-25'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:36.343231578Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-xjhr-fm27-4hmx'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-26717'
  - url: >-
      https://github.com/openfun/richie/commit/a1b5bbda3403d7debb466c303a32852925fcba5f
  - url: 'https://github.com/Rickidevs/CVE-2026-26717'
  - url: 'https://github.com/openfun/richie'
  - url: >-
      https://medium.com/@ordogh/cve-2026-26717-hmac-timing-attack-in-openfun-richie-lms-f04377efe83d?postPublishedType=repub
tags:
  - osv
  - pip
  - exploit-available
epss: 0.00508
epssPercentile: 0.40835
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/Rickidevs/CVE-2026-26717'
  checkedAt: '2026-09-25T08:20:53.723Z'
exploitAvailable: true
ingestedAt: '2026-07-13T18:58:05.178Z'
---

## Overview

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.

## Affected packages

- `richie < 3.3.0`

## Remediation

Upgrade to a patched release:

- `richie 3.3.0`