Vulnerability-Lookup

GHSA-9RHM-2H4X-JWMX

Vulnerability from github – Published: 2026-10-20 21:04 – Updated: 2026-10-20 21:04

Summary

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

Details

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.

Severity

5.7 (Medium)


                  
                    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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.a2aproject.sdk:a2a-java-sdk-parent"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.0.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-111763"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-522"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-20T21:04:16Z",
    "nvd_published_at": "2026-10-20T16:17:00Z",
    "severity": "MODERATE"
  },
  "details": "*Impact.** A malicious or compromised A2A agent can cause the client\u0027s 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.\n\n**Where.** `client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java:69` in `intercept`\n\n**What.** The `apiKeySecurityScheme.name()` field from the remote agent\u0027s AgentCard (untrusted, server-controlled data) is used directly as the HTTP header name when placing client credentials. Combined with `JdkA2AHttpClient`\u0027s `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.\n\n**Exploit scenario.** Client configures an API key credential for agent\u0027s security scheme `myAuth`. The malicious agent returns an AgentCard where `securitySchemes` includes `myAuth` as `APIKeySecurityScheme` with `name=\u0027X-Leaked-Cred\u0027` 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\u0027s credential.\n\n**Preconditions.**\n- Client application has configured API key credentials via `CredentialService` for the agent\u0027s security scheme\n- The agent is malicious or compromised (controls its own AgentCard response)\n- The default `JdkA2AHttpClient` is used (with `followRedirects=NORMAL`)\n- The JDK version does not strip custom headers on cross-origin redirects (all current versions)\n\n**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.\n\n**Verification.** 2/3 lens verifiers confirmed.",
  "id": "GHSA-9rhm-2h4x-jwmx",
  "modified": "2026-10-20T21:04:16Z",
  "published": "2026-10-20T21:04:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111763"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/pull/1097"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/a2aproject/a2a-java"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect"
}

CVE-2026-111763 (GCVE-0-2026-111763)

Vulnerability from cvelistv5 – Published: 2026-10-20 15:03 – Updated: 2026-10-20 15:03

Title

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

Summary

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.

Severity

5.7 (Medium)


                        
                          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

CWE

CWE-522 - Insufficiently Protected Credentials

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7639 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/a2aproject/a2a-java/security/a…	x_refsource_CONFIRM
https://github.com/a2aproject/a2a-java/security/a…	x_refsource_MISC
https://github.com/a2aproject/a2a-java/pull/1097	x_refsource_MISC
https://github.com/a2aproject/a2a-java/commit/2a3…	x_refsource_MISC
https://github.com/a2aproject/a2a-java/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
a2aproject	a2a-java	Affected: < 1.3.0.Final

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "a2a-java",
          "vendor": "a2aproject",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.3.0.Final"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027s security scheme and control of the agent\u0027s AgentCard and redirect response, but no additional client privileges. This issue is fixed in version 1.3.0.Final."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 5.7,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-522",
              "description": "CWE-522: Insufficiently Protected Credentials",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-20T15:03:28.034Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx"
        },
        {
          "name": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg"
        },
        {
          "name": "https://github.com/a2aproject/a2a-java/pull/1097",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/a2aproject/a2a-java/pull/1097"
        },
        {
          "name": "https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478e",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478e"
        },
        {
          "name": "https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final"
        }
      ],
      "source": {
        "advisory": "GHSA-9rhm-2h4x-jwmx",
        "discovery": "UNKNOWN"
      },
      "title": "A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-111763",
    "datePublished": "2026-10-20T15:03:28.034Z",
    "dateReserved": "2026-10-16T17:52:09.082Z",
    "dateUpdated": "2026-10-20T15:03:28.034Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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