Which versions of stoatchat are affected by CVE-2026-63306?

stoatchat versions before 0.13.5 contain a critical server-side request forgery (SSRF) vulnerability in the /proxy and /embed endpoints that allows unauthenticated attackers to force the server to…. A patch is available.

How to fix or mitigate CVE-2026-63306?

Within 24 hours, immediately disable or restrict access to the /proxy and /embed endpoints, and implement egress filtering at the network perimeter to block unauthorized outbound requests. Within 7 days, deploy web application firewall (WAF) rules to validate URL parameters against a whitelist of approved domains, implement DNS resolution filtering, and block requests targeting private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 127.0.0.1/8) and cloud metadata endpoints (169.254.169.254, any-ip.compute.internal). Within 30 days, upgrade to stoatchat 0.13.5 or later when released, conduct a complete audit of access logs and external connection records, and implement runtime request validation using an IP reputation service.

stoatchat CVE-2026-63306

Q: What is the CVSS score of CVE-2026-63306?

CVE-2026-63306 has a CVSS 4.0 base score of 9.2 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

EUVD-2026-44915 CRITICAL

Server-Side Request Forgery (SSRF) (CWE-918)

2026-07-16 VulnCheck

GHSA-j5jq-jcvc-gxxc

SSRF Stoatchat

9.2

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

9.2 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

8.6 HIGH

Unauthenticated low-complexity network SSRF (PR:N/AC:L); scope changes as the server pivots to internal systems (S:C) with high confidentiality but no integrity or availability impact.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Patch available

Jul 16, 2026 - 14:03 EUVD

Analysis Generated

Jul 16, 2026 - 13:21 vuln.today

CVE Published

Jul 16, 2026 - 12:19 cve.org

CRITICAL 9.2

DescriptionCVE.org

stoatchat before 0.13.5 contains an unauthenticated server-side request forgery vulnerability in the /proxy and /embed endpoints that accept arbitrary URLs without DNS resolution filtering or private IP range validation. Attackers can enumerate internal services, fingerprint applications, and reach instance metadata endpoints by supplying malicious URLs or leveraging redirect chains to access internal infrastructure.

AnalysisAI

Server-side request forgery in stoatchat before 0.13.5 allows remote unauthenticated attackers to coerce the server into making arbitrary outbound requests through the /proxy and /embed endpoints, which accept attacker-supplied URLs without DNS resolution filtering or private-IP validation. Reported by VulnCheck and carrying a CVSS 4.0 score of 9.2, it lets attackers enumerate internal services, fingerprint applications, and reach cloud instance-metadata endpoints. There is no public exploit identified at time of analysis and it is not listed in CISA KEV.

Technical ContextAI

stoatchat is an open-source chat application whose /proxy and /embed endpoints are designed to fetch remote content on behalf of clients (typically to render link previews/URL unfurling and to proxy external resources). The root cause is CWE-918 (Server-Side Request Forgery): the endpoints take a user-controlled URL and issue an outbound request without validating the resolved destination. Because there is no DNS-resolution filtering, the server will honor hostnames that resolve to internal/loopback/link-local addresses (e.g. 127.0.0.1, 10.0.0.0/8, 169.254.169.254), and because there is no private-IP range validation, redirect chains (an attacker-controlled public host that 30x-redirects to an internal target) can also bypass naive front-end checks. The affected component is identified by CPE cpe:2.3:a:stoatchat:stoatchat:*:*:*:*:*:*:*:*.

RemediationAI

Vendor-released patch: upgrade to stoatchat 0.13.5 or later, which is the primary and recommended fix, per the GitHub advisory GHSA-xhww-5g9p-vvq5 (https://github.com/stoatchat/stoatchat/security/advisories/GHSA-xhww-5g9p-vvq5) and the VulnCheck advisory (https://www.vulncheck.com/advisories/stoatchat-before-unauthenticated-ssrf-via-proxy-and-embed-endpoints). If immediate upgrade is not possible, restrict or disable the /proxy and /embed endpoints at a reverse proxy, which breaks link-preview/URL-unfurling functionality, and enforce egress filtering so the stoatchat host cannot reach internal RFC1918 ranges, loopback, link-local 169.254.0.0/16, and the cloud metadata endpoint 169.254.169.254 (side effect: legitimate internal fetches will also be blocked). On cloud instances, require IMDSv2 and disable IMDSv1 to blunt metadata theft even if SSRF succeeds. As defense-in-depth, add allowlist-based URL validation that resolves DNS and rejects private/reserved IPs and denies HTTP redirects to non-allowlisted hosts.