# CVE-2026-117504: a2aproject a2a-go denial of service in Distributed Manager Cancel

Source: https://junglewise.ai/threats/cve-2026-117504-a-vulnerability-was-identified-in-a2aproject-a2a-go-up-to-2-4-0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-117504 · Severity: medium · CVSS 5.3 · Published 2026-10-27

a2a-go is a Golang SDK for the Agent-to-Agent (A2A) protocol used in distributed systems. A denial of service vulnerability in the Distributed Manager's Cancel function allows attackers to exhaust system resources by triggering event-queue reader leaks through repeated cancellation operations, potentially disrupting task execution across the network.

Technologies: [A2aproject A2a-Go](https://junglewise.ai/threats/technologies/a2a-go). Vendors: [A2aproject](https://junglewise.ai/threats/vendors/a2aproject).

## Quick answers

**Is CVE-2026-117504 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-117504 being exploited in the wild.

**How severe is CVE-2026-117504?** Medium severity, with a CVSS score of 5.3, published 27 October 2026.

**Which products and versions are affected?** A2aproject A2a-Go up to 2.4.0.

**Is there a fix for CVE-2026-117504?** Yes: fixed in 2.5.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-117504 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-117504?** Check whether you run A2aproject A2a-Go at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2.5.0

## Technical details

The vulnerability is a resource leak in the Cancel function of internal/taskexec/distributed_manager.go: when CreateReader is called to create an event-queue reader, early exit paths (context-encoding failures, task-store errors, or already-canceled states) return without closing the reader, leaving the reader and its registration behind. This can be triggered remotely by an attacker invoking Cancel operations, causing cumulative reader leaks that exhaust system memory and event-queue capacity. The fix ensures all early-return paths after CreateReader properly close the reader via safeCloseReader.

## Affected products

- a2aproject a2a-go up to 2.4.0

## Timeline

- 2026-10-27: disclosed

## References

- [https://github.com/a2aproject/a2a-go/](https://github.com/a2aproject/a2a-go/)
- [https://github.com/a2aproject/a2a-go/commit/14e41a978b31e134ffa1170d8657f9dd98529aa3](https://github.com/a2aproject/a2a-go/commit/14e41a978b31e134ffa1170d8657f9dd98529aa3)

## Related threats

- [a2aproject a2a-go resource exhaustion in REST SSE handler](https://junglewise.ai/threats/cve-2026-117503-a-vulnerability-was-determined-in-a2aproject-a2a-go-up-to-2-4-0)
- [a2a-go information exposure through error message in CreateExecutor](https://junglewise.ai/threats/cve-2026-116478-a-vulnerability-was-detected-in-a2aproject-a2a-go-up-to-2-4-0)