# CVE-2026-102740: AsyncHttpClient: Resumable download index store is created world-readable and follows a planted symlink

> Local attackers can read sensitive download URLs or overwrite arbitrary files via symlink attacks in AsyncHttpClient's resumable download feature.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-102740, GHSA-cf59-3jcr-vfhw, UBUNTU-CVE-2026-102740

## What is CVE-2026-102740?

CVE-2026-102740 is a medium-severity path traversal vulnerability in AsyncHttpClient async-http-client, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The AsyncHttpClient library allows Java applications to execute HTTP requests and asynchronously process HTTP responses. From 2.0.0 until 2.16.1 and 3.0.12, PropertiesBasedResumableProcessor stores resumable download state at the predictable shared path $java.io.tmpdir/ahc/ResumableAsyncHandler.properties with default permissions and link-following file operations. A local user who can read the shared store can see download URLs, including embedded user information or query tokens. A local user who can write within or pre-create the affected shared store directory can plant a symbolic link that the client follows when saving state, truncating and overwriting a target file writable by the client process. The filesystem path is used when ResumableAsyncHandler decorates another AsyncHandler, while the no-argument constructors use a no-op processor and are unaffected. This issue is fixed in versions 2.16.1 and 3.0.12.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-61 (UNIX Symbolic Link (Symlink) Following), CWE-379 (Creation of Temporary File in Directory with Insecure Permissions)

## Which versions are affected by CVE-2026-102740?


## How do I fix CVE-2026-102740?

No fix has been published for CVE-2026-102740 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-102740 being exploited?

There is no known exploitation of CVE-2026-102740 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102740 and fix it if it is affected.

What it is: CVE-2026-102740 is a medium-severity path traversal vulnerability in AsyncHttpClient async-http-client, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102740 in the wild and no public exploit code.

Affected product: AsyncHttpClient async-http-client. 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-2026-102740/ (Markdown: https://insights.sbomify.com/CVE-2026-102740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102740
- OSV: https://osv.dev/vulnerability/CVE-2026-102740

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102740/
Summaries are generated and may contain mistakes; the official description above is the record.