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: 1. Accepts the broker-declared oversized frame size. 2. Allocates memory based on this oversized declaration. 3. 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. Source Code Location: https://github.com/rabbitmq/amqp091-go Affected Packages: - go:github.com/rabbitmq/amqp091-go, affected < 1.13.0, patched in 1.13.0 CWEs: - CWE-770: Allocation of Resources Without Limits or Throttling CVSS: - CVSS_V4: score 8.9, CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H References: - https://github.com/rabbitmq/amqp091-go/security/advisories/GHSA-6c5v-hqjr-5xxp - https://nvd.nist.gov/vuln/detail/CVE-2026-79921 - https://github.com/rabbitmq/amqp091-go/pull/353 - https://github.com/rabbitmq/amqp091-go/commit/6beb7b51f59e46ddcf8066ad498dad32491d3be0 - https://github.com/rabbitmq/amqp091-go/releases/tag/v1.13.0 - https://github.com/advisories/GHSA-6c5v-hqjr-5xxp