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Fencer Vulns
medium 5.8

CVE-2026-102740 json

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

published 2026-10-15 24 d ago modified 2026-10-16 23 d ago also EUVD-2026-102223

cvss
5.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

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.

Patch / fix

  • asynchttpclient_project async-http-client 2.16.1, 3.0.12

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-102740 updated cvss 5.8

org.asynchttpclient/async-http-client: AsyncHttpClient: Arbitrary file overwrite via insecure temporary file handling

  • Red Hat Fuse 7 async-http-client 2.6.0
    affected: workaround, no fix planned “Avoid using ResumableAsyncHandler on hosts with shared temp directories, or point the ahc resumable store at a private directory (upstream workaround from GHSA-cf59-3jcr-vfhw).”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
24 d ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L

Affected products

  • AsyncHttpClient async-http-client

Classification

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

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.