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CVE-2026-111763

MEDIUM 5.7

Published 2026-10-20 · Last modified 2026-10-21

A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Prior to 1.3.0.Final, a malicious or compromised remote agent can cause the default JDK-based client to forward a configured API key to a third-party server. When a client application configures credentials through `CredentialService`, `AuthInterceptor.intercept` in `client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java` uses `APIKeySecurityScheme.name()` from the remote AgentCard directly as the HTTP header name containing the credential, without checking that the declared location is HEADER. JdkA2AHttpClient uses followRedirects(NORMAL), so an agent-controlled cross-origin redirect forwards the custom credential-bearing header even when the standard Authorization header is stripped. The attack requires configured API key credentials for the agent's security scheme and control of the agent's AgentCard and redirect response, but no additional client privileges. This issue is fixed in version 1.3.0.Final.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.1%chance of exploitation in 30 days · 3rd percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

5.7CVSS 4.0 · MEDIUM

  • ConfidentialityHigh
  • IntegrityNone
  • AvailabilityNone

What an attacker needs

  • ⚠Access: Requires local access to the host
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable
  • ⚠Requirements: Specific conditions must be present

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors A2aproject

Products A2a Java

Weakness (CWE)

  • CWE-522: : Insufficiently Protected Credentials

CVSS vector

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

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • org.a2aproject.sdk:a2a-java-sdk-parent Maven

    pkg:maven/org.a2aproject.sdk/a2a-java-sdk-parent

    ECOSYSTEM range
    • All earlier versions (introduced 0)
    • Fixed boundary (excluded): 1.3.0.Final
    6 explicitly listed affected versions

    1.0.0.Alpha4, 1.0.0.Beta1, 1.0.0.CR1, 1.0.0.Final, 1.1.0.Final, 1.2.0.Final

    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9rhm-2h4x-jwmx/GHSA-9rhm-2h4x-jwmx.json"
  }
}
    GitHub Advisory Database · GHSA-9rhm-2h4x-jwmx · Updated 2026-10-21T03:11:56.125202083Z

All CVSS metrics

  • MEDIUM 5.7 v4.0 · CNA Primary
    CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
  • MEDIUM 5.7 v4.0 · NVD Secondary
    CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS