RabbitMQ: JSONReader in the default JSON-RPC mapper never terminates on truncated input, causing DoS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.9 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-106121: 0.53% estimated exploitation activity in the next 30 days; percentile 45.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary com.rabbitmq.tools.json.JSONReader.read() never returns when its input ends inside a quoted string or a // line comment. Both scanners walk the input with StringCharacterIterator.next() but only compare against a delimiter, so once the iterator reaches CharacterIterator.DONE (￿) they loop forever. The string scanner (string(), line 210, while (c != sep)) also appends ￿ to a StringBuilder every iteration, so it fills the heap and throws OutOfMemoryError, taking down the JVM. The comment scanner (skipWhiteSpace(), lines 89-92, while (c != '\n')) pins a thread at 100% CPU with no allocation. This is reachable with a single message. JsonRpcServer and JsonRpcClient fall back to DefaultJsonRpcMapper whenever no mapper is passed (JsonRpcServer.java:84 and :114, JsonRpcClient.java:186), and that mapper hands the raw message body straight to JSONReader.read() (DefaultJsonRpcMapper.java:42 for the server request, :52 for the client reply). A caller that can publish to the RPC request…

Published by the source

7 Oct 2026, 20:42 UTC

Last modified by the source

7 Oct 2026, 21:00 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cqgh-8p3p-mx4m

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-cqgh-8p3p-mx4m

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# Patch Next advisory brief: CVE-2026-106121

Advisory: RabbitMQ: JSONReader in the default JSON-RPC mapper never terminates on truncated input, causing DoS
IDs: CVE-2026-106121, GHSA-cqgh-8p3p-mx4m
Record: https://patchnext.com/advisories/cve-2026-106121 (revision 2, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.rabbitmq:amqp-client 5.36.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.rabbitmq:amqp-client: affected <= 5.36.0; fixed in 5.36.1

## Suggested inspection (read-only)
- Maven com.rabbitmq:amqp-client: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.rabbitmq:amqp-client.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-cqgh-8p3p-mx4m (OSV record GHSA-cqgh-8p3p-mx4m lists affected ranges: Maven com.rabbitmq:amqp-client >=0 <5.36.1 (fixed))
- Verified: https://github.com/advisories/GHSA-cqgh-8p3p-mx4m (GitHub-reviewed advisory GHSA-cqgh-8p3p-mx4m lists affected ranges: Maven com.rabbitmq:amqp-client >=0 <=5.36.0)

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