CVE-2026-111763
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
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
Exploit Intelligence
Low risk: more likely to be exploited than 3% of all known CVEs.
References
Related Vulnerabilities
Other CWE-522 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2019-17662 | Critical | 9.8 | 97% | - | - |
| CVE-2020-29583 | Critical | 9.8 | 90% | KEV | - |
| CVE-2021-30116 | Critical | 10.0 | 86% | KEV + Ransom | Fix |
| CVE-2024-44000 | Critical | 9.8 | 82% | - | Fix |
| CVE-2018-9160 | Critical | 9.8 | 76% | - | - |
| CVE-2017-9248 | Critical | 9.8 | 75% | KEV | Fix |
Common questions
How do I fix CVE-2026-111763?
No published fix for CVE-2026-111763 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-111763 being actively exploited?
Not that we know of. CVE-2026-111763 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.14% is the estimated probability that it will be exploited in the next 30 days. That is higher than 3% of all scored CVEs.
How severe is CVE-2026-111763?
CVE-2026-111763 has a CVSS v4 base score of 5.7, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-21.