CVE-2026-77405: RabbitMQ amqp091-go: Missing Explicit TLS Minimum Version Configuration In URI Parser

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• 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 0.3%, percentile 20: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 20% 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, tlsConfigFromURI in uri.go creates tls.Config values without setting MinVersion to tls.VersionTLS12. Builds using a Go runtime whose default permits TLS 1.0 or TLS 1.1 can therefore negotiate an obsolete protocol version when connecting through an amqps URI. A network attacker able to influence TLS negotiation with such a legacy build may weaken transport protection for AMQP messages and credentials. This issue is fixed in version 1.13.0.

From the GitHub advisory

Summary A structural security weakness exists in the AMQP client's TLS configuration generator (tlsConfigFromURI). When constructing a tls.Config object from an amqps:// connection URI, the library initializes the structure without explicitly defining the MinVersion field.

While modern versions of the Go compiler toolchain (Go 1.18+) default the implicit minimum version to TLS 1.2, this security posture relies entirely on an implicit toolchain dependency. If the library is compiled using legacy Go toolchains (Go

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Vulnerability Details

Mechanism The vulnerability lies in the lack of an explicit safety floor when assigning configurations inside the URI component:

Weakness type: CWE-326, CWE-316.

Product: github.com/rabbitmq/amqp091-go (Go) · Assigned by: GitHub_M · Published: 2026-09-16

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: high (needs special conditions)
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.28% probability of exploitation activity in the next 30 days; percentile 20.

Timeline

• 2026-09-16 — CVE record published by GitHub_M
• 2026-09-17 — GitHub-reviewed advisory GHSA-33mj-cw25-m34h published (critical)
• 2026-09-18 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-33mj-cw25-m34h github.com
2. CVE.org record CVE-2026-77405 cve.org
3. NVD entry CVE-2026-77405 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical Go advisories · Today’s Security Digest