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HIGH severity

Goroutine Leak in Abacus SSE ImplementationGHSA-vh64-54px-qgf8

HIGHFix: JasonLovesDoggo/abacus@78fdb9b

GHSA-vh64-54px-qgf8 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in github.com/jasonlovesdoggo/abacus. A fix is available for github.com/jasonlovesdoggo/abacus — see the affected versions and patch details below.

Also known asCVE-2025-27421GO-2025-3498
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for GHSA-vh64-54px-qgf8.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs36th percentile — riskier than 36% of all scored CVEsHighest risk
0.00%0.30%0.61%0.91%0.2%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/jasonlovesdoggo/abacus

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Goroutine Leak in Abacus SSE Implementation

Summary

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.

POC

Impact

This vulnerability affects all versions of Abacus prior to v1.4.0. The issue causes:

  • Permanent unresponsiveness of the /stream endpoint after prolonged use
  • Memory growth that stabilizes at a high level but prevents proper functionality
  • Selective denial of service affecting only SSE connections while other endpoints remain functional
  • Accumulated orphaned goroutines that cannot be garbage collected
  • High resource consumption under sustained client connection/disconnection patterns

Systems running Abacus in production with client applications that frequently establish and terminate SSE connections are most vulnerable. The issue becomes particularly apparent in high-traffic environments or during connection stress testing.

Patches

The vulnerability has been patched in Abacus v1.4.0. The fix includes:

  1. Implementing buffered channels to prevent blocking operations during cleanup
  2. Adding proper mutex-protected cleanup logic to ensure resources are released exactly once
  3. Implementing timeout protection for channel operations to prevent deadlocks
  4. Ensuring consistent cleanup when connections terminate unexpectedly
  5. Adding improved monitoring for client disconnections using request context
  6. Restructuring the event broadcasting system to safely handle client removal

Users should upgrade to v1.4.0 or later versions as soon as possible.

Workarounds

If upgrading is not immediately possible, the following workarounds can help mitigate the issue:

  1. Limit maximum connections: Configure your reverse proxy to limit the maximum number of concurrent connections to the /stream endpoints.

  2. Implement request timeouts: Configure your infrastructure to terminate long-lived SSE connections after a reasonable period.

  3. Restart regularly: Schedule regular restarts of the Abacus service to reclaim resources.

  4. Monitor memory usage: Set up alerts for abnormal memory growth patterns.

  5. Separate instance for SSE: Run a dedicated Abacus instance solely for handling SSE connections, allowing it to be restarted without affecting the main API functionality.

References

For More Information

Please contact the Abacus security team at [email protected] for additional information or to report further security issues.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/jasonlovesdoggo/abacusall versions0.0.0-20250302043802-898ff1204e11go get github.com/jasonlovesdoggo/abacus@v0.0.0-20250302043802-898ff1204e11

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/jasonlovesdoggo/abacus, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/jasonlovesdoggo/abacus to 0.0.0-20250302043802-898ff1204e11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vh64-54px-qgf8 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

## Goroutine Leak in Abacus SSE Implementation ### Summary 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, ca
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Goroutine Leak in Abacus SSE Implementation (High 7.5)