How severe is CVE-2026-63335?

No CVSS score has been assigned to CVE-2026-63335 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-63335?

CVE-2026-63335 affects the following packages: com.rabbitmq:amqp-client (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-63335?

Update com.rabbitmq:amqp-client to 5.31.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-63335 is resolved across your whole dependency graph.

How do I detect CVE-2026-63335 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.rabbitmq:amqp-client, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-63335 if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is CVE-2026-63335 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-63335 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-63335?

CVE-2026-63335 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 42th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-63335?

CVE-2026-63335 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-63335 published, and has it been updated?

CVE-2026-63335 was published on August 18, 2026 and was last updated on September 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-63335 — amqp-client

Fix: rabbitmq/rabbitmq-java-client@3173534

CVE-2026-63335 is a Improper Input Validation vulnerability in com.rabbitmq:amqp-client. A fix is available for com.rabbitmq:amqp-client — see the affected versions and patch details below.

RabbitMQ Java client malformed body frame triggers raw command assembler exception

Also known asGHSA-qx7j-jv8m-fppr

Published

Aug 18, 2026

Updated

Sep 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-63335.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

☕com.rabbitmq:amqp-client

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Summary

RabbitMQ Java Client's inbound AMQP command assembly accepts a content header declaring a small body and then processes a larger body frame by throwing a raw UnsupportedOperationException from CommandAssembler. A broker peer that the client has connected to can use this malformed frame sequence to fail frame processing and tear down the client connection instead of receiving a clean protocol-level malformed-frame error.

This was discovered based on an existing vulnerability CVE-2017-15699.

Details

Inbound frames enter the client through SocketFrameHandler.readFrame, which returns frames parsed from the peer-controlled input stream (src/main/java/com/rabbitmq/client/impl/SocketFrameHandler.java:197). AMQConnection.MainLoop reads each frame (src/main/java/com/rabbitmq/client/impl/AMQConnection.java:692) and dispatches non-zero-channel frames to the channel while the connection is open (src/main/java/com/rabbitmq/client/impl/AMQConnection.java:748 and src/main/java/com/rabbitmq/client/impl/AMQConnection.java:766). The channel then passes the frame to the current command assembler through AMQChannel.handleFrame and AMQCommand.handleFrame (src/main/java/com/rabbitmq/client/impl/AMQChannel.java:121, src/main/java/com/rabbitmq/client/impl/AMQCommand.java:114). When a content-bearing method is followed by a content header, CommandAssembler.consumeHeaderFrame records the header's declared body size in remainingBodyBytes after only checking it against the configured maximum (src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:126 through src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:139). The body-frame path subtracts the received payload length from that remaining count before validating that the payload fits (src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:145 through src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:149), so a body frame larger than the declared size drives the count negative and reaches the raw UnsupportedOperationException at src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:150 and src/main/java/com/rabbitmq/client/impl/CommandAssembler.java:151. AMQConnection catches the resulting throwable in frame processing and performs connection failure handling and final shutdown (src/main/java/com/rabbitmq/client/impl/AMQConnection.java:695 through src/main/java/com/rabbitmq/client/impl/AMQConnection.java:705).

PoC

poc.zip

bash ./poc/run.sh

Exception in thread "main" java.lang.UnsupportedOperationException: %%%%%% FIXME unimplemented

The UnsupportedOperationException: %%%%%% FIXME unimplemented fingerprint is the raw exception thrown at the negative remainingBodyBytes check in CommandAssembler.consumeBodyFrame. This line shows the malformed declared-size/body-size sequence reached the vulnerable assembler path.

Impact

The attacker model is a remote AMQP broker peer that the RabbitMQ Java Client application has accepted, including a malicious broker endpoint, a compromised broker, or routing that sends the client to an attacker-controlled peer. The peer needs a non-zero open channel that can receive a content-bearing server-to-client method such as basic.deliver, then sends the method frame, a content header declaring a body below the configured maximum, and a body frame whose payload exceeds that declared size. Under those conditions, the peer can force frame processing to fail with UnsupportedOperationException and close the AMQP connection, producing a client-side denial of service for work depending on that connection; the finding does not indicate memory corruption, data disclosure, or code execution.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.rabbitmq:amqp-client`	all versions	5.31.0`com.rabbitmq:amqp-client:5.31.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.rabbitmq:amqp-client, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.rabbitmq:amqp-client to 5.31.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-63335 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Frequently Asked Questions

### Summary RabbitMQ Java Client's inbound AMQP command assembly accepts a content header declaring a small body and then processes a larger body frame by throwing a raw `UnsupportedOperationException` from `CommandAssembler`. A broker peer that the client has connected to can use this malformed frame sequence to fail frame processing and tear down the client connection instead of receiving a clean protocol-level malformed-frame error. This was discovered based on an existing vulnerability CVE-2017-15699. ### Details Inbound frames enter the client through `SocketFrameHandler.readFrame`, wh

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