CVE-2026-90820: Auth Bypass (CVSS 4.3)

Description

A security vulnerability has been detected in a2aproject a2a-java 1.2.0. The impacted element is the function AuthorizationRequestHandlerDecorator.onListTasks of the file server-common/src/main/java/org/a2aproject/sdk/server/requesthandlers/AuthorizationRequestHandlerDecorator.java. Such manipulation leads to missing authorization. The attack can be launched remotely. Upgrading to version 1.3.0 is sufficient to resolve this issue. The name of the patch is e9a1abf9c90c02b16d17293afdc3cc2f555d63a6. The affected component should be upgraded.

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CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

CWE-863 Incorrect Authorization

References

Other References

https://github.com/a2aproject/a2a-java/ https://github.com/a2aproject/a2a-java/commit/e9a1abf9c90c02b16d17293afdc3cc2f555d63a6 https://github.com/a2aproject/a2a-java/pull/1038 https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final https://vuldb.com/cve/CVE-2026-90820 https://vuldb.com/submit/925152 https://vuldb.com/vuln/403323 https://vuldb.com/vuln/403323/cti

Frequently Asked Questions

What is CVE-2026-90820? +

A security vulnerability has been detected in a2aproject a2a-java 1.2.0. The impacted element is the function AuthorizationRequestHandlerDecorator.onListTasks of the file server-common/src/main/java/org/a2aproject/sdk/server/requesthandlers/AuthorizationRequestHandlerDecorator.java. Such manipulation leads to missing authorization. The attack can be launched remotely. Upgrading to version 1.3.0 is sufficient to resolve this issue. The name of the patch is e9a1abf9c90c02b16d17293afdc3cc2f555d63a6. The affected component should be upgraded. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-90820? +

CVE-2026-90820 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-90820? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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