# CVE-2026-90820: Missing authorization in a2a-java

> Remote attackers can bypass authorization checks in the onListTasks function to access task data without proper permissions.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-vmmr-97qx-h8c4

## What is CVE-2026-90820?

CVE-2026-90820 is a medium-severity missing authorization vulnerability in a2aproject a2a-java, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-863 (Incorrect Authorization), CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-90820?


## How do I fix CVE-2026-90820?

No fix has been published for CVE-2026-90820 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90820 being exploited?

There is no known exploitation of CVE-2026-90820 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90820 and fix it if it is affected.

What it is: CVE-2026-90820 is a medium-severity missing authorization vulnerability in a2aproject a2a-java, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90820 in the wild and no public exploit code.

Affected product: a2aproject a2a-java. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90820/ (Markdown: https://insights.sbomify.com/CVE-2026-90820/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90820
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90820
- OSV: https://osv.dev/vulnerability/CVE-2026-90820

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90820/
Summaries are generated and may contain mistakes; the official description above is the record.