CVE-2025-27421

CVE-2025-27421 is a high-severity uncontrolled resource consumption vulnerability in github.com/jasonlovesdoggo/abacus (go), affecting versions < 0.0.0-20250302043802-898ff1204e11. It is fixed in 0.0.0-20250302043802-898ff1204e11.

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Summary

Goroutine Leak in Abacus SSE Implementation

Goroutine Leak in Abacus SSE Implementation

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

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.

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.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2025-27421 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20250302043802-898ff1204e11); upgrading removes the vulnerable code path.

Affected versions

github.com/jasonlovesdoggo/abacus (< 0.0.0-20250302043802-898ff1204e11)

Security releases

github.com/jasonlovesdoggo/abacus → 0.0.0-20250302043802-898ff1204e11 (go)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

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.

Frequently Asked Questions

  1. What is CVE-2025-27421? CVE-2025-27421 is a high-severity uncontrolled resource consumption vulnerability in github.com/jasonlovesdoggo/abacus (go), affecting versions < 0.0.0-20250302043802-898ff1204e11. It is fixed in 0.0.0-20250302043802-898ff1204e11. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
  2. How severe is CVE-2025-27421? CVE-2025-27421 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
  3. Which versions of github.com/jasonlovesdoggo/abacus are affected by CVE-2025-27421? github.com/jasonlovesdoggo/abacus (go) versions < 0.0.0-20250302043802-898ff1204e11 is affected.
  4. Is there a fix for CVE-2025-27421? Yes. CVE-2025-27421 is fixed in 0.0.0-20250302043802-898ff1204e11. Upgrade to this version or later.
  5. Is CVE-2025-27421 exploitable, and should I be worried? Whether CVE-2025-27421 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
  6. What actually determines whether CVE-2025-27421 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
  7. How do I fix CVE-2025-27421? Upgrade github.com/jasonlovesdoggo/abacus to 0.0.0-20250302043802-898ff1204e11 or later.

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