Summary
RabbitMQ amqp091-go: Silent Data Truncation and State Corruption via Shortstr Integer Overflow
A data integrity and protocol corruption vulnerability exists in the AMQP client's property serialization logic. When encoding AMQP short string (shortstr) fields, such as identifiers, routing strings, and content metadata, the length of the string is explicitly cast to a fixed-size 8-bit unsigned integer (uint8).
If an application provides a property string exceeding 255 bytes, the length counter silently wraps around (e.g., a length of 300 wraps to 44). As a result, the parser writes only a truncated portion of the string into the outgoing connection buffer without returning an error. This leads to silent data corruption, broken RPC routing, and unpredictable broker-side state behavior.
Vulnerability Details
Mechanism
The vulnerability resides in the wire-level serialization logic for application publishing properties:
// write.go:246
length := uint8(len(b)) // wraps silently when len(b) > 255 (e.g., 300 -> 44)
Because Go allows silent integer truncation during explicit type casting, lengths larger than $2^8 - 1$ lose their most significant bits. The underlying stream writer reads length to determine how many bytes to pull from the buffer. Because no error or boundary check accompanies this truncation, the application believes the full payload was transmitted successfully.
Affected Properties
This truncation behavior affects every standard AMQP field serialized as a shortstr:
CorrelationIdReplyToMessageIdExpirationUserIdAppIdContentTypeContentEncodingType
Attack Vector
An attacker who can influence metadata fields processed by an upstream application (such as a user-supplied tracking ID or a long content-type header) can exploit this to break system components:
- Targeting RPC Routing: A user passes a malicious or overly long
CorrelationIdof 300 bytes through an application endpoint. - Silent Truncation: The library wraps the length value to 44, transmitting only the first 44 bytes to the rabbitMQ broker.
- Broken Correlation: When the service processes the request and responds, the replying consumer attempts to route the message using the full 300-byte identifier. Because the broker only recognizes the truncated 44-byte ID, the reply loop breaks silently, leading to hanging processes or data leaks across transaction boundaries.
Impact
The critical consequence is silent protocol desynchronization at the application layer. The underlying TCP stream remains framed properly (because the shortened length matches the bytes written), but the business logic is corrupted. Distributed transactions, request-reply correlations, and tracing headers are truncated, causing downstream systems to drop messages or route them to incorrect consumers.
An arithmetic operation produces a value that exceeds the integer type's maximum, causing it to wrap to an unexpected small value. Typical impact: incorrect size calculations leading to heap overflows or logic errors.
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-2026-77408? CVE-2026-77408 is a critical-severity integer overflow or wraparound vulnerability in github.com/rabbitmq/amqp091-go (go), affecting versions < 1.13.0. It is fixed in 1.13.0. An arithmetic operation produces a value that exceeds the integer type's maximum, causing it to wrap to an unexpected small value.
- Which versions of github.com/rabbitmq/amqp091-go are affected by CVE-2026-77408? github.com/rabbitmq/amqp091-go (go) versions < 1.13.0 is affected.
- Is there a fix for CVE-2026-77408? Yes. CVE-2026-77408 is fixed in 1.13.0. Upgrade to this version or later.
- Is CVE-2026-77408 exploitable, and should I be worried? Whether CVE-2026-77408 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-2026-77408 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-2026-77408? Upgrade
github.com/rabbitmq/amqp091-goto 1.13.0 or later.