Summary
amqp091-go has a Potential Memory Exhaustion/Protocol Violation via Broker-Controlled Oversized Payload
Summary
A vulnerability exists in the amqp091-go client library where a compromised or malicious AMQP broker can force the client to allocate resources for and process content body frames that exceed the negotiated frame_max limit. This can lead to unexpected memory consumption or application-layer denial of service (DoS), bypassing the protocol's built-in framing constraints.
Details
During a standard AMQP 0-9-1 connection handshake, the client and the broker negotiate a maximum frame size (frame_max), for example, 4096 bytes.
However, after negotiation, a malicious broker can send a valid basic.deliver sequence containing a content body frame whose header declares a payload size larger than the negotiated frame_max. Instead of enforcing the agreed-upon limit and closing the connection with a frame-error (as mandated by the AMQP 0-9-1 specification), the amqp091-go client:
- Accepts the broker-declared oversized frame size.
- Allocates memory based on this oversized declaration.
- Reads the payload, assembles it into the message, and delivers it to the consumer.
Impact
- Denial of Service (DoS): If a broker sends extremely large frame sizes, it can trigger significant memory allocations on the client side, potentially leading to Out-Of-Memory (OOM) crashes.
- Protocol Violation: The client fails to enforce negotiated connection parameters, trusting the broker implicitly even after constraints have been established.
Impact
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-79921? CVE-2026-79921 is a high-severity allocation of resources without limits or throttling vulnerability in github.com/rabbitmq/amqp091-go (go), affecting versions < 1.13.0. It is fixed in 1.13.0. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of github.com/rabbitmq/amqp091-go are affected by CVE-2026-79921? github.com/rabbitmq/amqp091-go (go) versions < 1.13.0 is affected.
- Is there a fix for CVE-2026-79921? Yes. CVE-2026-79921 is fixed in 1.13.0. Upgrade to this version or later.
- Is CVE-2026-79921 exploitable, and should I be worried? Whether CVE-2026-79921 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-79921 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-79921? Upgrade
github.com/rabbitmq/amqp091-goto 1.13.0 or later.