Your RSA-2048 keys break in 2030. Find every one of them before attackers do.
☕ Maven
Not in CISA KEV

CVE-2026-111763 — a2a-java-sdk-parent

Fix: a2aproject/a2a-java@2a36530

CVE-2026-111763 is a CWE-522 vulnerability in org.a2aproject.sdk:a2a-java-sdk-parent. A fix is available for org.a2aproject.sdk:a2a-java-sdk-parent — see the affected versions and patch details below.

A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect

Also known asGHSA-9rhm-2h4x-jwmx
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-111763.

EPSS Exploitation Probability

via FIRST.org ↗
0.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs3th percentile — riskier than 3% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
☕org.a2aproject.sdk:a2a-java-sdk-parent

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact.* A malicious or compromised A2A agent can cause the client's API key credential to be forwarded to an arbitrary third-party server. The agent serves an AgentCard with an APIKeySecurityScheme specifying a custom header name, then responds with an HTTP redirect. The JDK HttpClient follows the redirect and forwards the custom header containing the credential, since only the standard Authorization header may be stripped on cross-origin redirects.

Where. client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java:69 in intercept

What. The apiKeySecurityScheme.name() field from the remote agent's AgentCard (untrusted, server-controlled data) is used directly as the HTTP header name when placing client credentials. Combined with JdkA2AHttpClient's followRedirects(NORMAL) policy, credentials under custom header names survive cross-origin redirects (only Authorization is stripped on newer JDKs), allowing a malicious agent to leak client credentials to third-party servers. Additionally, AuthInterceptor does not check that location==HEADER before placing the credential as a header.

Exploit scenario. Client configures an API key credential for agent's security scheme myAuth. The malicious agent returns an AgentCard where securitySchemes includes myAuth as APIKeySecurityScheme with name='X-Leaked-Cred' and location=HEADER. AuthInterceptor places the credential in the X-Leaked-Cred header. The agent responds with HTTP 302 redirect to https://evil.com/collect. JdkA2AHttpClient follows the redirect, forwarding all custom headers including X-Leaked-Cred to evil.com. The attacker captures the client's credential.

Preconditions.

  • Client application has configured API key credentials via CredentialService for the agent's security scheme
  • The agent is malicious or compromised (controls its own AgentCard response)
  • The default JdkA2AHttpClient is used (with followRedirects=NORMAL)
  • The JDK version does not strip custom headers on cross-origin redirects (all current versions)

Fix. Validate the APIKeySecurityScheme.name() field against a whitelist of safe header names. Check that apiKeySecurityScheme.location() equals Location.HEADER before placing the credential as a header. Consider using followRedirects(NEVER) and implementing manual redirect handling that strips all authentication headers on cross-origin redirects.

Verification. 2/3 lens verifiers confirmed.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.a2aproject.sdk:a2a-java-sdk-parentall versions1.3.0.Finalorg.a2aproject.sdk:a2a-java-sdk-parent:1.3.0.Final

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.a2aproject.sdk:a2a-java-sdk-parent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.a2aproject.sdk:a2a-java-sdk-parent to 1.3.0.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-111763 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

*Impact.** A malicious or compromised A2A agent can cause the client's API key credential to be forwarded to an arbitrary third-party server. The agent serves an AgentCard with an `APIKeySecurityScheme` specifying a custom header name, then responds with an HTTP redirect. The JDK HttpClient follows the redirect and forwards the custom header containing the credential, since only the standard `Authorization` header may be stripped on cross-origin redirects. **Where.** `client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java:69` in `inte
O3 Security · Impact-Aware SCA

Is CVE-2026-111763 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2026-111763: a2a-java-sdk — Fixed in 1.3.0.Final