What is CVE-2026-63096?

CVE-2026-63096 is a medium-severity vulnerability in Matrix-Org Dendrite, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-07-17.

How severe is CVE-2026-63096?

Medium severity. CVSS v3 base score is 5.8 out of 10.

SSRF in Matrix-Org Dendrite

CVE-2026-63096

Dendrite through 0.13.8 contains a server-side request forgery vulnerability that allows unauthenticated attackers to cause the server to open outbound TLS connections to arbitrary hosts and ports by supplying an unvalidated serverName parameter to the legacy media download endpoint. Attackers can exploit distinguishable error response classes and leaked internal IP addresses in error messages to perform blind port scanning and enumerate internal network topology.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2026-07-17 · last modified 2026-07-17.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.7th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.7% 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

Matrix-Org Dendrite — versions 0

Weakness classification (CWE)

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

References

Researcher Disclosure (technical-description, exploit)
www.vulncheck.com/advisories/dendrite-ssrf-via-unauthenticated-legacy-media-dow… (third-party-advisory)

Frequently asked questions

What is CVE-2026-63096?: CVE-2026-63096 is a medium-severity vulnerability in Matrix-Org Dendrite, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-07-17.
How severe is CVE-2026-63096?: Medium severity. CVSS v3 base score is 5.8 out of 10.