CVE-2026-86178: Auth Bypass (CVSS 5.4)

Description

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.

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CVSS v3.1 Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

References

Other References

https://github.com/geo-chen/oss/blob/main/Pixelfed.md https://github.com/pixelfed/pixelfed https://github.com/pixelfed/pixelfed/blob/v0.12.9/app/Http/Controllers/StoryComposeController.php#L487-L501 https://github.com/pixelfed/pixelfed/blob/v0.12.9/app/Http/Controllers/StoryComposeController.php#L566-L580 https://github.com/pixelfed/pixelfed/blob/v0.12.9/routes/web-api.php#L154-L155 https://www.vulncheck.com/advisories/pixelfed-through-0.12.9-unauthorized-story-access-via-api

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-86178? +

CVE-2026-86178 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0018, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-86178? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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