XSS in Seaweedfs
CVE-2026-58371
SeaweedFS before 4.30 reflects the callback query parameter verbatim into responses served with Content-Type application/javascript in the shared writeJson helper (weed/server/common.go), with no callback-name validation, no X-Content-Type-Options: nosniff header, and no CORS allow-list. Every JSON endpoint that uses writeJson - including the unauthenticated master endpoints /dir/status, /dir/lookup and /cluster/status, the volume server /status, and the filer directory listing, all reachable in the default configuration (no -whiteList, no security.toml, bound to 0.0.0.0) - can therefore be loaded cross-origin via a script tag with a chosen callback, letting a third-party web page read cluster topology, volume server URLs and gRPC ports, file identifiers, and directory listings. Because the callback string is reflected at the start of the body and no nosniff header is sent, MIME-sniffing clients may also interpret the reflected content as HTML.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Seaweedfs — versions 0
Weakness classification (CWE)
References
- github.com/seaweedfs/seaweedfs/releases/tag/4.30 (release-notes)
- github.com/seaweedfs/seaweedfs/pull/9686 (issue-tracking)
- github.com/seaweedfs/seaweedfs/commit/77dcb20a7485074d37340985d53103f94538abe6 (patch)
- github.com/geo-chen/oss/blob/main/seaweedfs.md (technical-description, exploit)
- www.vulncheck.com/advisories/seaweedfs-cross-origin-information-disclosure-via-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-58371?
- CVE-2026-58371 is a low-severity vulnerability in Seaweedfs, classified under Cross-site Scripting. CVSS score: 3.1/10. Published 2026-06-30.
- How severe is CVE-2026-58371?
- Low severity. CVSS v3 base score is 3.1 out of 10.