CVE-2026-63096Public exploitNetwork attack vector

Internal network enumeration via unvalidated media serverName

Published Jul 17, 2026 · Updated Jul 17, 2026

Server-side request forgery in Matrix.org Foundation Dendrite 0.13.8 and earlier allows remote attackers to initiate outbound TLS connections. The unauthenticated legacy media download handler accepts serverName from the request path, checks only that it is nonempty, and passes it to federation resolution without blocking private, loopback, or caller-selected host-port destinations. Any client that can reach the Matrix client API can distinguish connection errors and receive resolved internal IP addresses, enabling blind port scans and internal topology enumeration while direct reads remain limited to TLS-speaking services.

CVSS severity6.9
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side request forgery in Matrix.org Foundation Dendrite 0.13.8 and earlier allows remote attackers to initiate outbound TLS connections. The unauthenticated legacy media download handler accepts serverName from the request path, checks only that it is nonempty, and passes it to federation resolution without blocking private, loopback, or caller-selected host-port destinations. Any client that can reach the Matrix client API can distinguish connection errors and receive resolved internal IP addresses, enabling blind port scans and internal topology enumeration while direct reads remain limited to TLS-speaking services.

The record

CVE
CVE-2026-63096
Published
Jul 17, 2026
Updated
Jul 17, 2026
Vendor
Matrix.org Foundation
Product
Dendrite
Classifications
CWE-918, T1046
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=0.13.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Matrix.org Foundation · Dendriteversion=0 <=0.13.8

Published CVSS scores

6.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N
5.3Researcher disclosureCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1046Network Service Discovery

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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