---
title: "CVE-2026-77411: RabbitMQ amqp091-go: Protocol Desynchronization and Frame Injection via Integer Overflow in readLongstr"
url: https://erroneo.us/security/cve/CVE-2026-77411/
description: "CVE-2026-77411 (github.com/rabbitmq/amqp091-go (Go)): RabbitMQ amqp091-go is a Go AMQP 0.9.1 client. Prior to 1.13.0, readLongstr in read.go returns an…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-16
date_modified: 2026-09-17
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-77411"
kev: false
cvss: 9.5
epss: 0.00524
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/rabbitmq/amqp091-go (Go) < 1.13.0, fixed in 1.13.0 . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- Go `github.com/rabbitmq/amqp091-go` < 1.13.0 → fixed: 1.13.0

## Affected products (CVE record)

- rabbitmq amqp091-go: < 1.13.0

## Severity

- GitHub_M CVSS 4.0: 9.5 `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`
- GitHub CVSS 4.0: 9.5 `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`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.52% probability of exploitation activity in the next 30 days; percentile 44.

## Sources

- [GitHub Advisory GHSA-c5pq-fr2g-9jpf](https://github.com/advisories/GHSA-c5pq-fr2g-9jpf)
- [CVE.org record CVE-2026-77411](https://www.cve.org/CVERecord?id=CVE-2026-77411)
- [NVD entry CVE-2026-77411](https://nvd.nist.gov/vuln/detail/CVE-2026-77411)
- [github.com](https://github.com/rabbitmq/amqp091-go/security/advisories/GHSA-c5pq-fr2g-9jpf)
- [github.com](https://github.com/rabbitmq/amqp091-go/pull/347)
- [github.com](https://github.com/rabbitmq/amqp091-go/commit/143c1ace5fa7344cee135e5c7d22970f0de68282)
- [github.com](https://github.com/rabbitmq/amqp091-go/releases/tag/v1.13.0)

---
Source page: https://erroneo.us/security/cve/CVE-2026-77411/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt