CVE-2025-27421 Goroutine Leak in Abacus SSE Implementation
Attackers can cause resource exhaustion and denial of service by disconnecting from the SSE stream, preventing new connections.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-27421?
CVE-2025-27421 is a high-severity denial of service vulnerability in JasonLovesDoggo abacus, published on 3 Mar 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Abacus is a highly scalable and stateless counting API. A critical goroutine leak vulnerability has been identified in the Abacus server's Server-Sent Events (SSE) implementation. The issue occurs when clients disconnect from the /stream endpoint, as the server fails to properly clean up resources and terminate associated goroutines. This leads to resource exhaustion where the server continues running but eventually stops accepting new SSE connections while maintaining high memory usage. The vulnerability specifically involves improper channel cleanup in the event handling mechanism, causing goroutines to remain blocked indefinitely. This vulnerability is fixed in 1.4.0.
Which versions are affected by CVE-2025-27421?
3 open source packages ship an affected version, including github.com/jasonlovesdoggo/abacus.
| Package | Affected | Fixed in |
|---|---|---|
github.com/jasonlovesdoggo/abacus Go | All versions | 0.0.0-20250302043802-898ff1204e11 |
github.com/jasonlovesdoggo/abacus Go | All versions | 0.0.0-20250302043802-898ff1204e11 |
github.com/jasonlovesdoggo/abacus Go | All versions | 0.0.0-20250302043802-898ff1204e11 |
How do I fix CVE-2025-27421?
Upgrade github.com/jasonlovesdoggo/abacus to 0.0.0-20250302043802-898ff1204e11 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-2025-27421 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-27421 exists.
Sources
Also known as GHSA-vh64-54px-qgf8, GO-2025-3498.