CVE-2026-58371

Description

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.

CVSS v3.1 Score

3.1

LOW

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

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

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/geo-chen/oss/blob/main/seaweedfs.md https://github.com/seaweedfs/seaweedfs/commit/77dcb20a7485074d37340985d53103f94538abe6 https://github.com/seaweedfs/seaweedfs/pull/9686 https://github.com/seaweedfs/seaweedfs/releases/tag/4.30 https://www.vulncheck.com/advisories/seaweedfs-cross-origin-information-disclosure-via-unvalidated-jsonp-callback-parameter

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 3.1 (LOW).

How severe is CVE-2026-58371? +

CVE-2026-58371 has a CVSS v3.1 score of 3.1 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-58371? +

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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