CVE-2026-77368 (CVSS 7.6)

Description

SeaweedFS is a distributed storage system for files and blobs. In version 4.39, the filer's TUS resumable-upload handler checks JWT allowed_prefixes scoping only when a session is created, letting a low-privilege tenant hijack another tenant's upload session to write content to filer paths their own token forbids. The HEAD, PATCH, and DELETE verbs that act on an existing session by its id never verify that the session's stored target path falls within the caller's allowed prefixes, so a tenant who obtains another upload's session identifier can PATCH attacker bytes into it and, on completion, have the file land at the victim's out-of-scope path. The same token can also DELETE other tenants' sessions and HEAD them to read upload progress and size, defeating the JWT prefix isolation. This vulnerability only affects deployments that configure filer JWT signing and have TUS uploads enabled. This issue is fixed in version 4.40.

Is your site exposed to CVE-2026-77368?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.6

HIGH

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

EPSS — Exploit Prediction

0.0022

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-639 CWE-639

References

Other References

https://github.com/seaweedfs/seaweedfs/commit/ce82e3a057080162a9fba11889157d2255815f71 https://github.com/seaweedfs/seaweedfs/commit/fa549e9c83b7799d512157d728f52052912831af https://github.com/seaweedfs/seaweedfs/security/advisories/GHSA-99q7-x53r-6j4g

Frequently Asked Questions

What is CVE-2026-77368? +

SeaweedFS is a distributed storage system for files and blobs. In version 4.39, the filer's TUS resumable-upload handler checks JWT allowed_prefixes scoping only when a session is created, letting a low-privilege tenant hijack another tenant's upload session to write content to filer paths their own token forbids. The HEAD, PATCH, and DELETE verbs that act on an existing session by its id never verify that the session's stored target path falls within the caller's allowed prefixes, so a tenant who obtains another upload's session identifier can PATCH attacker bytes into it and, on completion, have the file land at the victim's out-of-scope path. The same token can also DELETE other tenants' sessions and HEAD them to read upload progress and size, defeating the JWT prefix isolation. This vulnerability only affects deployments that configure filer JWT signing and have TUS uploads enabled. This issue is fixed in version 4.40. It has a CVSS v3.1 base score of 7.6 (HIGH).

How severe is CVE-2026-77368? +

CVE-2026-77368 has a CVSS v3.1 score of 7.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0022, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-77368? +

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.

Related Vulnerabilities

CVE-2026-40570

FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, the `load_customer_info` action in `POST /conversation/ajax` …

CVE-2026-9152

A missing authentication vulnerability exists in the Altium 365 SearchService. A legacy SOAP endpoint exposes search index operations without requiring …

CVE-2026-40866

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-40865

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-6375

A vulnerability in SpiceJet’s booking API allows unauthenticated users to query passenger name records (PNRs) without any access controls. Because …

CVE-2025-15626

Authenticated user can bypass authorization in Ribblr - Crochet & Knitting iOS application

CVE-2026-77368