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.
CVE-2026-111763
This medium-severity CVE scores 5.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1% (3rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.7
- EG Score
- 5.7MEDIUMlow confidence
- EG Risk
- 26EG Risk 26/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity57% × 45%Impact severity (EG Severity): CVSS 5.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0% × 40%No KEV listing, EG-KEV tier or EPSS when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.1%
- EPSS %ILE
- 3rd
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.7): severity, escalated by confirmed exploitation. This CVE's 5.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.7 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.1% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 20, 2026
Last Modified
October 21, 2026
Advisory Details (5)
Auto-updated Oct 20, 2026v1.3.0.Final
Patch available: a2aproject/a2a-java v1.3.0.Final
https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Finalcommit 2a36530d75e1 (a2aproject/a2a-java)
Patch available: a2aproject/a2a-java v1.3.0.Final (contains commit 2a36530d75e1)
https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478efix: prevent credential leakage via header injection and redirects
Patch available: a2aproject/a2a-java v1.3.0.Final (PR #1097 merged 2026-08-26)
https://github.com/a2aproject/a2a-java/pull/1097Android synchronous POST overrides the GHSA-9rhm redirect fix and forwards credentials across authorities · Advisory · a2aproject/a2a-java · GitHub
https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rggClient credentials sent under server-controlled HTTP header name, enabling leakage via redirect · Advisory · a2aproject/a2a-java · GitHub
https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmxVendor Advisories for CVE-2026-111763(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
Maven(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.a2aproject.sdk:a2a-java-sdk-parent | 1.0.0.Alpha4 ... 1.2.0.Final (6 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 6× in last 7d / 6× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
- 2026-10-21 16:31 UTCEG score recompute
- 2026-10-21 16:01 UTCEG score recompute
- 2026-10-20 16:28 UTCEG score recompute
- 2026-10-20 15:24 UTCEG score recomputeFirst assessed: 5.7 MEDIUM
- 2026-10-20 15:21 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-111763?
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Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-111763
Is Your Infrastructure Affected by CVE-2026-111763?
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