rabbitmq-c CVE-2026-44236

Requires the rabbitmq-c client (versions < 0.16.0) to establish an AMQP connection to an attacker-controlled or compromised broker, OR an on-path/MITM attacker intercepting plaintext (non-TLS) AMQP traffic to inject a malicious connection.tune frame with frame_max below AMQP_FRAME_MIN_SIZE. Limiting factors: the client must initiate the connection (UI:R), the malicious frame is only accepted during the amqp_login() handshake, and TLS-protected connections to trusted brokers eliminate the on-path variant. There is no server-side or unsolicited exposure - the victim is the connecting client.

The vendor CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H = 7.1) is internally consistent with the description: the flaw is a client-side heap buffer overflow triggered by a MALICIOUS or compromised AMQP server (or an on-path attacker on plaintext AMQP), so 'PR:N' means no authentication against the client, but exploitation is gated on the client voluntarily connecting to attacker-controlled infrastructure (UI:R). This is NOT a remotely-reachable, unsolicited server-side flaw - the attacker must sit where the client connects. No EPSS score, KEV listing, or POC was provided, and the description explicitly states 'Code execution is theoretically possible but was not demonstrated,' so the realistic, confirmed impact is memory corruption and denial of service (A:H), not RCE. This is a genuine but conditional issue: real priority only for deployments where rabbitmq-c clients connect over untrusted networks or to untrusted brokers. The 'RCE' tag overstates the confirmed impact given C:N and the vendor's own 'not demonstrated' caveat. No signal indicates widespread or active exploitation - treat as a patch-on-cycle library update rather than an emergency.

An attacker who controls or has compromised an AMQP broker (or performs on-path interception of plaintext, non-TLS AMQP traffic) waits for a rabbitmq-c client to call amqp_login(). During the connection.tune handshake the malicious server returns an undersized frame_max below AMQP_FRAME_MIN_SIZE; the client sizes its outbound buffer to that value and immediately serializes connection.tune-ok, writing past the undersized heap allocation and corrupting the heap, crashing the client. No public exploit code was identified and code execution was not demonstrated.