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Response snapshot Oct 27, 2026, 02:10 UTC

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VulnerabilityCVE-2026-111765

A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix

The GHSA-9rhm fix added this safe setting in AndroidA2AHttpClient.createConnection(): connection.setInstanceFollowRedirects(false);

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.8% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: org.a2aproject.sdk:a2a-java-sdk-http-client-android: 1.3.2.Final. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-4fpj-g9jf-9rgg (opens a new tab)

What happened

The GHSA-9rhm fix added this safe setting in AndroidA2AHttpClient.createConnection():

connection.setInstanceFollowRedirects(false);

The synchronous POST builder later overwrites it:

private boolean followRedirects = true;

Continue reading

public A2AHttpResponse post() throws IOException { HttpURLConnection connection = createConnection("POST", false); connection.setInstanceFollowRedirects(followRedirects); // ... }

The second assignment wins. JSONRPCTransport and RestTransport both add interceptor-produced headers and call synchronous post() without setting followRedirects(false).

On Android's repackaged OkHttp implementation, a cross-authority redirect strips Authorization but retains nonstandard request headers. AuthInterceptor permits four nonstandard authentication header names:

X-API-Key API-Key X-Auth-Token X-Authentication

I confirmed that the exact v1.3.1.Final Maven artifact forwards complete synthetic values under all four names to a second loopback authority. I also reproduced the supported AuthInterceptor to Android POST path. Explicitly calling followRedirects(false) returns the original 302 and produces no request to the collector.

All test traffic stayed on two ephemeral 127.0.0.1 listeners. All credentials were synthetic FULCRUM-SYNTHETIC-* values.

Reproduction

I have attached AndroidA2AHttpClientRedirectTest.java. Copy it to:

extras/http-client-android/src/test/java/org/a2aproject/sdk/client/http/android/

Run:

mvn -pl extras/http-client-android -am \ -Dtest=AndroidA2AHttpClientRedirectTest \ -Dsurefire.failIfNoSpecifiedTests=false test

On unpatched current main, the default test fails with:

Android synchronous POST must retain the documented no-redirect default expected: but was:

The explicit followRedirects(true) control still passes.

The separate exact-artifact fixture passed three consecutive runs. Its relevant output was:

default status=200 x-api-key=FULCRUM-SYNTHETIC-DIRECT authorization=null method=GET control-followRedirects-false status=302 collectorHits=0 interceptor-chain status=200 x-api-key=FULCRUM-SYNTHETIC-INTERCEPTOR collectorHits=1 header-matrix name=X-API-Key forwarded=FULCRUM-SYNTHETIC-X-API-Key header-matrix name=API-Key forwarded=FULCRUM-SYNTHETIC-API-Key header-matrix name=X-Auth-Token forwarded=FULCRUM-SYNTHETIC-X-Auth-Token header-matrix name=X-Authentication forwarded=FULCRUM-SYNTHETIC-X-Authentication

Impact and limitations

The demonstrated impact is disclosure of a complete API key or authentication token to a different authority. I am not claiming subsequent use of the credential, integrity impact, availability impact, code execution, or host compromise.

A fully malicious origin already receives the credential on the first request. The additional boundary matters most when redirect or front-door behavior is compromised separately from the component that handles request credentials, or when different parts of the origin operate in different trust domains.

The 7.5 score applies to an autonomous client where no human action is needed after the remote endpoint returns the redirect. If the Android workflow requires a person to select or invoke the remote agent, UI:R gives a 6.5 score. I have kept both vectors because that deployment detail affects severity but not the underlying behavior.

These are suggested scores, consistent with the policy's statement that actual CVSS depends on the specific deployment context. The same policy labels the parent credential-redirect property as moderate.

Scope and prior art

This path appears to fall directly under the project's current security model:

1. extras/http-client-android and the client transports are listed as in scope. 2. Remote AgentCard and response data are treated as attacker-relevant inputs. 3. A malicious or compromised remote agent is part of the client-side adversary model. 4. Section 8 says automatic redirects are disabled in all JDK, Vert.x, and Android implementations to prevent credential leakage. 5.

Section 13 defines a violation of a Section 8 property through the covered input and adversary as VALID. 6. Section 13a lists missed call sites and under-strength mitigations as new findings after an incomplete fix. 7. Section 14 records the original issue as fixed by disabling redirects across all HTTP client implementations. The Android synchronous path directly contradicts that recorded repair state.

This report does not claim that an AgentCard SecurityScheme declaration enforces authentication. The application has already configured the credential, and the shipped AuthInterceptor places it in an allowed header. The failure is the Android client's default redirect behavior after that point. It does not depend on a custom SPI, an insecure configuration flag, a test-only component, server-side authentication, or any of the recurring non-findings listed in Section 11a.

GHSA-9rhm is the direct parent finding. Its fix commit says redirects were disabled across all clients, but the Android POST-level override remains in 1.3.0.Final, 1.3.1.Final, and current main. I searched the public issues and pull requests on September 5 and found PR #1097, but no report covering this surviving synchronous Android path.

The other three published advisories address server authorization defaults, push-notification SSRF, and credential logging. They do not cover this Android client path.

Suggested fix

The smallest compatible change is:

- private boolean followRedirects = true; + private boolean followRedirects = false;

This keeps followRedirects(true) available as an explicit opt-in. The attached regression passes three out of three times after the change. The Android module and its reactor dependencies pass 455 tests with no failures. The full repository test run passes 2,914 tests with no failures or errors. It reports 127 skips when using the project's documented -DskipDockerTests=true option inside the isolated build container.

References

Security property: https://git

Affected package ranges reported by GitHub: org.a2aproject.sdk:a2a-java-sdk-http-client-android: >= 1.3.0.Final, <= 1.3.1.Final

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.8%

Scored Percentile 56.4%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-4fpj-g9jf-9rgg (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-4fpj-g9jf-9rgg, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-111765 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-111765, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 22). A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix (CVE-2026-111765). https://kevwire.com/record/CVE-2026-111765

MLA

"A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix (CVE-2026-111765)." KEVWire, 22 Oct. 2026, kevwire.com/record/CVE-2026-111765.

Chicago

KEVWire. "A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix (CVE-2026-111765)." Last modified October 22, 2026. https://kevwire.com/record/CVE-2026-111765.

Evidence summary (plain text)

A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix (Oct 20, 2026).
The GHSA-9rhm fix added this safe setting in
AndroidA2AHttpClient.createConnection():

 connection.setInstanceFollowRedirects(false);
CVSS 7.5 (version 3.1; evidence as of Oct 22, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-111765).
EPSS 0.8% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-111765&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-4fpj-g9jf-9rgg: https://github.com/advisories/GHSA-4fpj-g9jf-9rgg
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNTo1Mjo1NlrOAAfxiA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
NVD CVE-2026-111765: https://nvd.nist.gov/vuln/detail/CVE-2026-111765
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=6000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-111765&date=2026-10-26
Record ID: CVE-2026-111765.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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