CVE-2026-110103: bbs-go through 4.4.6 Stored XSS via Image Upload Content-Type

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-16
Weakness: CWE-79

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.

Affected products

mlogclub bbs-go: through 4.4.6

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

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