Vulnerability-Lookup

CVE-2026-77406 (GCVE-0-2026-77406)

Vulnerability from cvelistv5 – Published: 2026-09-16 14:37 – Updated: 2026-09-16 18:35

Title

RabbitMQ amqp091-go: Consumer Message Flooding via Signed-to-Unsigned Integer Casting in Qos Configuration

Summary

RabbitMQ amqp091-go is a Go AMQP 0.9.1 client. Prior to 1.13.0, Channel.Qos in channel.go accepts negative prefetchCount and prefetchSize integers and casts them directly to uint16 and uint32 fields in the basic.qos method because validateQos is absent. Values such as -1 therefore wrap to 65535 or 4294967295 instead of being rejected. An application that permits untrusted configuration of these Qos values can unintentionally request extremely large prefetch limits, allowing a broker to deliver enough queued messages to exhaust client memory and disrupt processing. This issue is fixed in version 1.13.0.

Severity

8.2 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 18:18 UTC

CWE

CWE-195 - Signed to Unsigned Conversion Error

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/rabbitmq/amqp091-go/security/a…	x_refsource_CONFIRM
https://github.com/rabbitmq/amqp091-go/pull/351	x_refsource_MISC
https://github.com/rabbitmq/amqp091-go/commit/3b8…	x_refsource_MISC
https://github.com/rabbitmq/amqp091-go/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
rabbitmq	amqp091-go	Affected: < 1.13.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-77406

Vulnerability from fkie_nvd - Published: 2026-09-16 15:17 - Updated: 2026-09-16 19:17

Severity

8.2 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/rabbitmq/amqp091-go/commit/3b879e1d1d25b544e26b3bc3d7db3213203c0f3b
	security-advisories@github.com	https://github.com/rabbitmq/amqp091-go/pull/351
	security-advisories@github.com	https://github.com/rabbitmq/amqp091-go/releases/tag/v1.13.0
	security-advisories@github.com	https://github.com/rabbitmq/amqp091-go/security/advisories/GHSA-rm6m-hrcw-jw33

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "product": "amqp091-go",
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    }
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  "lastModified": "2026-09-16T19:17:38.663",
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GHSA-RM6M-HRCW-JW33

Vulnerability from github – Published: 2026-09-17 17:04 – Updated: 2026-09-17 17:04

Summary

RabbitMQ amqp091-go: Consumer Message Flooding via Signed-to-Unsigned Integer Casting in Qos Configuration

Details

Summary

A logic and resource exhaustion vulnerability exists in the AMQP client's Quality of Service (Qos) configuration method. The Qos function accepts signed integers (int) for the prefetchCount and prefetchSize parameters but casts them directly to unsigned integers (uint16 and uint32, respectively) when formatting the wire-level frame.

If a developer passes a negative integer (such as -1) to these parameters—frequently intended as a sentinel value meaning "no change" or "no limit"—the application performs an implicit signed-to-unsigned conversion. This wraps the values to their absolute maximum limit ($65535$ and $4294967295$). Consequently, a consumer expecting restricted message delivery rates is suddenly flooded with an unlimited volume of messages, potentially exhausting memory resources and crashing the application.

Vulnerability Details

Mechanism

The bug manifests during the structural assignment inside the channel's Qos method:

// channel.go:795-796
PrefetchCount: uint16(prefetchCount),  // -1 wraps to 65535
PrefetchSize:  uint32(prefetchSize),   // -1 wraps to 4294967295

In Go, converting a negative signed integer to an unsigned integer shifts the value via two's complement arithmetic. Because no boundary validation or signedness check occurs prior to the cast: * Passing -1 for prefetchCount yields a wire value of 65535. * Passing -1 for prefetchSize yields a wire value of 4294967295.

Impact

The AMQP broker interprets a prefetch-count of 65535 as an instruction to dispatch messages to the consumer with virtually no concurrency limits.

If the application is processing heavy payloads or relies on strict rate-limiting to maintain stability, this unexpected flood will cause rapid heap memory growth, unmanageable processing queues, and an eventual Out-Of-Memory (OOM) termination.

Attack Vector

An attacker who can manipulate configuration files, environmental variables, or API inputs that dictate client Qos settings can trigger an application-layer Denial of Service:

Malicious Input: An attacker sets a service's prefetch configuration parameter to -1.
Implicit Overflow: The application initializes the channel, executes Qos(-1, ...), and transmits an unintended maximum-capacity request to the RabbitMQ/AMQP broker.
Consumer Exhaustion: The broker flushes the entire contents of the queue directly into the client consumer's network buffer, bypassing expected application concurrency barriers and inducing a crash.

Severity

8.2 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/rabbitmq/amqp091-go"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.13.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77406"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-195"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-17T17:04:05Z",
    "nvd_published_at": "2026-09-16T15:17:49Z",
    "severity": "HIGH"
  },
  "details": "## Summary\nA logic and resource exhaustion vulnerability exists in the AMQP client\u0027s Quality of Service (`Qos`) configuration method. The `Qos` function accepts signed integers (`int`) for the `prefetchCount` and `prefetchSize` parameters but casts them directly to unsigned integers (`uint16` and `uint32`, respectively) when formatting the wire-level frame.\n\nIf a developer passes a negative integer (such as `-1`) to these parameters\u2014frequently intended as a sentinel value meaning \"no change\" or \"no limit\"\u2014the application performs an implicit signed-to-unsigned conversion. This wraps the values to their absolute maximum limit ($65535$ and $4294967295$). Consequently, a consumer expecting restricted message delivery rates is suddenly flooded with an unlimited volume of messages, potentially exhausting memory resources and crashing the application.\n\n---\n\n## Vulnerability Details\n\n### Mechanism\nThe bug manifests during the structural assignment inside the channel\u0027s `Qos` method:\n\n```go\n// channel.go:795-796\nPrefetchCount: uint16(prefetchCount),  // -1 wraps to 65535\nPrefetchSize:  uint32(prefetchSize),   // -1 wraps to 4294967295\n```\n\nIn Go, converting a negative signed integer to an unsigned integer shifts the value via two\u0027s complement arithmetic. Because no boundary validation or signedness check occurs prior to the cast:\n* Passing `-1` for `prefetchCount` yields a wire value of `65535`.\n* Passing `-1` for `prefetchSize` yields a wire value of `4294967295`.\n\n### Impact\nThe AMQP broker interprets a `prefetch-count` of `65535` as an instruction to dispatch messages to the consumer with virtually no concurrency limits. \n\nIf the application is processing heavy payloads or relies on strict rate-limiting to maintain stability, this unexpected flood will cause rapid heap memory growth, unmanageable processing queues, and an eventual Out-Of-Memory (OOM) termination.\n\n---\n\n## Attack Vector\nAn attacker who can manipulate configuration files, environmental variables, or API inputs that dictate client Qos settings can trigger an application-layer Denial of Service:\n\n1. **Malicious Input:** An attacker sets a service\u0027s prefetch configuration parameter to `-1`.\n2. **Implicit Overflow:** The application initializes the channel, executes `Qos(-1, ...)`, and transmits an unintended maximum-capacity request to the RabbitMQ/AMQP broker.\n3. **Consumer Exhaustion:** The broker flushes the entire contents of the queue directly into the client consumer\u0027s network buffer, bypassing expected application concurrency barriers and inducing a crash.",
  "id": "GHSA-rm6m-hrcw-jw33",
  "modified": "2026-09-17T17:04:05Z",
  "published": "2026-09-17T17:04:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rabbitmq/amqp091-go/security/advisories/GHSA-rm6m-hrcw-jw33"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77406"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rabbitmq/amqp091-go/pull/351"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rabbitmq/amqp091-go/commit/3b879e1d1d25b544e26b3bc3d7db3213203c0f3b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/rabbitmq/amqp091-go"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rabbitmq/amqp091-go/releases/tag/v1.13.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "RabbitMQ amqp091-go: Consumer Message Flooding via Signed-to-Unsigned Integer Casting in Qos Configuration"
}

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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-77406 (GCVE-0-2026-77406)

FKIE_CVE-2026-77406

GHSA-RM6M-HRCW-JW33

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