Auth bypass in Lycheeorg Lychee
CVE-2026-39957
Lychee is a free, open-source photo-management tool. Prior to 7.5.4, a SQL operator-precedence bug in SharingController::listAll() causes the orWhereNotNull('user_group_id') clause to escape the ownership filter applied by the when() block. Any authenticated non-admin user with upload permission who owns at least one album can retrieve all user-group-based sharing permissions across the entire instance, including private albums owned by other users. This vulnerability is fixed in 7.5.4.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 23.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Lycheeorg Lychee — versions < 7.5.4
Weakness classification (CWE)
References
- github.com/LycheeOrg/Lychee/security/advisories/GHSA-4v4c-g2jv-4g25 (Exploit, Patch, Vendor Advisory)
- github.com/LycheeOrg/Lychee/pull/4264 (Patch, Issue Tracking)
- github.com/LycheeOrg/Lychee/commit/76a3f0513eca6458bf7f8c337c1ad65e59b22bcb (Patch)
Frequently asked questions
- What is CVE-2026-39957?
- CVE-2026-39957 is a medium-severity vulnerability in Lycheeorg Lychee, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2026-04-09.
- How severe is CVE-2026-39957?
- Medium severity. CVSS v3 base score is 4.3 out of 10.