High Cross-site scripting

CVE-2026-66077 — RabbitMQ: Stored XSS via TLS peer-certificate DN in management UI

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, The management UI uses EJS 1.0 in which <%= ... %> does NOT HTML-escape. connection.ejs:135 renders <%= connection.ssl_details.peer_cert_subject %> (and peer_cert_issuer) directly into the page. The same pattern appears in streamConnection.ejs:102,106,110. The values come from rabbit_ssl:peer_cert_subject/1 which formats the DN as a string without HTML escaping. The verifier corrected the original researcher's claim: this is reachable only when the listener is configured with verify_peer (so the certificate must be signed by a CA in the broker's trust store, not arbitrary self-signed); however, in deployments using mTLS for client authentication, any user who can request a certificate from the organisational CA controls the Subject CN. An attacker who can obtain a TLS client certificate signed by a CA the broker trusts (with verify_peer enabled) can embed JavaScript in the certificate's Subject DN. When any administrator views that connection in the management UI, the script executes in the admin's browser session, allowing full account takeover (create users, export definitions, etc.). The management UI's CSP includes 'unsafe-inline', so inline script execution is not blocked. Preconditions include TLS listener configured with ssl_options.verify = verify_peer Attacker can obtain a CA-signed client certificate with attacker-chosen Subject (e.g. self-service corporate PKI, or rabbitmq_trust_store plugin in use) Administrator views the connection detail page. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6.

Published Sep 23, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Rabbitmq

Rabbitmq-server

CVSS base

7.3

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Rabbitmq Rabbitmq-server).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Rabbitmq	Rabbitmq-server	version >= 3.13.0, < 3.13.15version >= 4.0.0, < 4.0.20version >= 4.1.0, < 4.1.11version >= 4.2.0, < 4.2.6	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Attack requirements

Present

Privileges required

Low

User interaction

Active

Scope

Confidentiality (vulnerable system)

High

Integrity (vulnerable system)

High

Availability (vulnerable system)

Low

Confidentiality (subsequent)

None

Integrity (subsequent)

None

Availability (subsequent)

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.3	CVSS 4.0	High	—	—	security-advisories@github.com via NIST National Vulnerability Database
7.3	CVSS 4.0	High	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:L/SC:N/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

(score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-79 · Cross-site Scripting (XSS)

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Monitor CSP violation reports and script payloads in reflected parameters.

web/proxy/WAF logsnetwork IDS/IPSapplication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · rabbitmq/rabbitmq-server
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 7.3
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Undergoing Analysis
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 23, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

2 on the record

github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-rjcf-35r5-xw38
x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6
x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Rabbitmq
every CVE for this vendor

Cross-site scripting
same class

CWE-79
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-67418 RabbitMQ MQTT 5: inapplicable PUBLISH property disconnects matching subscribers 1d
Medium CVE-2026-67414 RabbitMQ AMQP 1.0 parser: amplification memory-exhaustion DoS via zero-width array aggregation 1d
Medium CVE-2026-67416 RabbitMQ: AMQP 1.0 symbolic body descriptor prefix collisions bypass validation 1d
Medium CVE-2026-67421 RabbitMQ: Stored HTML Injection in RabbitMQ Management OAuth Error Handling 20d
High CVE-2026-67410 RabbitMQ: OAuth2 Client Secret Exposed via Unauthenticated JavaScript Endpoint 20d
High CVE-2026-67412 RabbitMQ: Federation upstream skips vhost authorization allowing cross-vhost message access 20d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-66077 is "RabbitMQ: Stored XSS via TLS peer-certificate DN in management UI", rated High. It affects Rabbitmq-server (Rabbitmq); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.3 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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