Auth bypass in Pixelfed
CVE-2026-86178
Pixelfed through 0.12.9 fails to validate follower status in StoryComposeController react and comment endpoints, allowing authenticated users to access follower-only stories. Attackers can enumerate sequential story IDs and submit reactions or comments to retrieve story media URLs and author information without following the account.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.6% 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
Weakness classification (CWE)
References
- github.com/geo-chen/oss/blob/main/Pixelfed.md (exploit, third-party-advisory)
- github.com/pixelfed/pixelfed (product)
- github.com/pixelfed/pixelfed/blob/v0.12.9/app/Http/Controllers/StoryComposeCont… (technical-description)
- github.com/pixelfed/pixelfed/blob/v0.12.9/app/Http/Controllers/StoryComposeCont… (technical-description)
- github.com/pixelfed/pixelfed/blob/v0.12.9/routes/web-api.php (technical-description)
- www.vulncheck.com/advisories/pixelfed-through-0.12.9-unauthorized-story-access-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86178?
- CVE-2026-86178 is a medium-severity vulnerability in Pixelfed, classified under Missing Authorization. CVSS score: 5.4/10. Published 2026-09-05.
- How severe is CVE-2026-86178?
- Medium severity. CVSS v3 base score is 5.4 out of 10.