CVE-2026-110103: XSS (CVSS 5.4)

Description

bbs-go through 4.4.6 contains a stored cross-site scripting vulnerability that allows authenticated users to upload HTML or SVG files by spoofing the multipart Content-Type in POST /api/upload. Attackers can upload script-bearing documents served inline from /res and send their URLs to administrators, executing script on the forum's origin.

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CVSS v3.1 Score

5.4

MEDIUM

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

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.12%

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-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/handlers/api/upload_handlers.go#L36-L54 https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/uploader/uploader.go#L90-L121 https://github.com/mlogclub/bbs-go/commit/5bebf98bb9e0ac5162d4f8faf7a65fc0d496a362 https://github.com/mlogclub/bbs-go/issues/305 https://github.com/mlogclub/bbs-go/pull/306 https://www.vulncheck.com/advisories/bbs-go-through-4.4.6-stored-xss-via-image-upload-content-type

Frequently Asked Questions

What is CVE-2026-110103? +

bbs-go through 4.4.6 contains a stored cross-site scripting vulnerability that allows authenticated users to upload HTML or SVG files by spoofing the multipart Content-Type in POST /api/upload. Attackers can upload script-bearing documents served inline from /res and send their URLs to administrators, executing script on the forum's origin. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-110103? +

CVE-2026-110103 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 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-110103? +

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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