# CVE-2026-113704: a2a-rs server-side request forgery in push notification handler

Source: https://junglewise.ai/threats/cve-2026-113704-a-vulnerability-has-been-found-in-a2aproject-a2a-rs-up-to-0-4-3  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-113704 · Severity: high · CVSS 7.3 · Published 2026-10-20

a2a-rs is a Rust SDK that includes a push notification server component. The vulnerability allows remote attackers to perform server-side request forgery (SSRF) by manipulating the URL configuration for push notifications, potentially enabling them to access internal services, metadata endpoints, or private networks from the affected server.

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

## Quick answers

**Is CVE-2026-113704 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-113704 being exploited in the wild.

**How severe is CVE-2026-113704?** High severity, with a CVSS score of 7.3, published 20 October 2026.

**Which products and versions are affected?** A2aproject A2a-Rs up to 0.4.3.

**Is there a fix for CVE-2026-113704?** No fixed version is recorded yet. The patch enables URL validation by default via HttpPushSenderConfig::validate_urls. If upgrading is not immediately possible, deployments relying on loopback or private-network webhooks must explicitly disable validation as this is now rejected by default.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-20"},{"kind":"patched","at":"2026-10-20","note":"Patch commit 2ba50176ea9f222d9a7d0f0e8cfe6fae7cf4c224"}] If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-113704 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-113704?** Check whether you run A2aproject A2a-Rs 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


The patch enables URL validation by default via HttpPushSenderConfig::validate_urls. If upgrading is not immediately possible, deployments relying on loopback or private-network webhooks must explicitly disable validation as this is now rejected by default.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-20"},{"kind":"patched","at":"2026-10-20","note":"Patch commit 2ba50176ea9f222d9a7d0f0e8cfe6fae7cf4c224"}]

## Technical details

The HttpPushSender function in the push notification handler accepted arbitrary URLs from the TaskPushNotificationConfig parameter without proper validation, allowing SSRF attacks. The vulnerability affects a2a-rs versions up to 0.4.3. The fix introduces URL validation that rejects loopback, RFC 1918 private ranges, link-local, IPv6 ULA, and well-known metadata endpoints.

## Affected products

- a2aproject a2a-rs up to 0.4.3

## References

- [https://github.com/a2aproject/a2a-rs/](https://github.com/a2aproject/a2a-rs/)
- [https://github.com/a2aproject/a2a-rs/commit/2ba50176ea9f222d9a7d0f0e8cfe6fae7cf4c224](https://github.com/a2aproject/a2a-rs/commit/2ba50176ea9f222d9a7d0f0e8cfe6fae7cf4c224)

## Related threats

- [a2a-rs race condition in InMemoryTaskStore update](https://junglewise.ai/threats/cve-2026-113707-a-security-flaw-has-been-discovered-in-a2aproject-a2a-rs-up-to-0)
- [a2aproject a2a-rs information disclosure in error handling](https://junglewise.ai/threats/cve-2026-113705-a-vulnerability-was-determined-in-a2aproject-a2a-rs-up-to-0-4-3)