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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
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.
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.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-102740 being exploited?
There is no known exploitation of CVE-2026-102740 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-102740, GHSA-cf59-3jcr-vfhw, UBUNTU-CVE-2026-102740.