CVE-2026-111762 — a2a-java-sdk-transport-re…
Fix: a2aproject/a2a-java@8882710CVE-2026-111762 is a CWE-532 vulnerability in org.a2aproject.sdk:a2a-java-sdk-transport-rest. A fix is available for org.a2aproject.sdk:a2a-java-sdk-transport-rest — see the affected versions and patch details below.
A2A Java SDK: Push notification credentials logged in cleartext on protobuf parse failure
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
org.a2aproject.sdk:a2a-java-sdk-transport-restReal-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.* Push notification bearer tokens and authentication credentials submitted by clients are written to server log files in cleartext. Any operator, log aggregation system, or attacker with log access can read these secrets and use them to authenticate to the client's push notification endpoints, potentially sending forged task status updates.
Where. transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java:676 in parseRequestBody
What. The parseRequestBody method logs the entire JSON request body at SEVERE level when JsonFormat.parser().merge() throws InvalidProtocolBufferException. This method is called from createTaskPushNotificationConfiguration (line 377), where the body contains client-supplied push notification bearer tokens (field token) and authentication credentials (field authentication.credentials). These secrets are written to server log files in full.
Exploit scenario. A client creates a push notification configuration by POSTing to /v1/tenants/{tenant}/tasks/{taskId}/pushNotificationConfigs with a body containing {"url": "https://client.example.com/webhook", "token": "secret-bearer-token", "authentication": {"scheme": "Bearer", "credentials": "oauth-access-token"}, "extraField": "value"}. The extra field causes JsonFormat.parser().merge() to throw InvalidProtocolBufferException. The entire body including secret-bearer-token and oauth-access-token is logged at SEVERE level. An attacker with log access retrieves the cleartext credentials.
Preconditions.
- Attacker must have access to server log files (centralized logging, log aggregation, shared infrastructure, or insider access)
- Push notification capability must be enabled
- A request body must fail protobuf deserialization while being valid JSON (unknown fields with strict parsing, schema mismatches)
Fix. Do not log the raw request body. Log only a sanitized summary — body length and content type, not content. Replace the log call with something like: log.log(Level.SEVERE, "Error parsing JSON request body (length={0})", body != null ? body.length() : 0).
Verification. 3/3 lens verifiers confirmed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.a2aproject.sdk:a2a-java-sdk-transport-rest | all versions | 1.3.0.Finalorg.a2aproject.sdk:a2a-java-sdk-transport-rest:1.3.0.Final |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.a2aproject.sdk:a2a-java-sdk-transport-rest, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.a2aproject.sdk:a2a-java-sdk-transport-rest to 1.3.0.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-111762 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2026-111762 in your dependencies?
Find it across Maven, including transitive dependencies.