CVE-2025-3864 Connection pool exhaustion in hackney
Remote attackers can exhaust connection pools by triggering 307 redirects, causing denial of service in applications using the hackney library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-3864?
CVE-2025-3864 is a low-severity denial of service vulnerability in hackney, published on 28 May 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Hackney fails to properly release HTTP connections to the pool after handling 307 Temporary Redirect responses. Remote attackers can exploit this to exhaust connection pools, causing denial of service in applications using the library. Fix for this issue has been included in 1.24.0 release.
Weakness: CWE-772
Which versions are affected by CVE-2025-3864?
2 open source packages ship an affected version, including hackney.
| Package | Affected | Fixed in |
|---|---|---|
hackney Hex | All versions | 1.24.0 |
hackney Hex | All versions | 1.24.0 |
How do I fix CVE-2025-3864?
Upgrade hackney to 1.24.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-3864 being exploited?
There is no known exploitation of CVE-2025-3864 in the wild and no public exploit code.
Sources
Also known as GHSA-9fm9-hp7p-53mf.