klever-go: REST API slow-header connection exhaustion via Gin Engine.Run

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-52880: 0.49% estimated exploitation activity in the next 30 days; percentile 42.05 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Klever seednode REST API starts a Gin engine with Engine.Run(restAPIInterface). In Gin v1.9.1, Engine.Run calls Go's default http.ListenAndServe, which constructs an HTTP server without application-level ReadHeaderTimeout, ReadTimeout, or MaxHeaderBytes limits. An unauthenticated client that can reach a REST listener bound with Klever's documented --rest-api-interface :8080 all-interface option can hold incomplete HTTP headers open indefinitely. In a local proof against the real cmd/seednode/api.Start path on v1.7.17, 120 slow-header connections caused 20/20 legitimate /log probes to fail with accept: too many open files. A fixed control using the same Gin router behind an explicit http.Server with ReadHeaderTimeout, ReadTimeout, and MaxHeaderBytes retained 0 slow connections and served 20/20 probes. This report is distinct from the P2P advisories and from my direct-message goroutine report. This finding concerns Klever-owned HTTP REST startup code (cmd/seednode/api and…

Published by the source

5 Jun 2026, 16:41 UTC

Last modified by the source

9 Jun 2026, 18:40 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-w4c6-7r69-w7j9

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# Patch Next advisory brief: CVE-2026-52880

Advisory: klever-go: REST API slow-header connection exhaustion via Gin Engine.Run
IDs: CVE-2026-52880, GHSA-w4c6-7r69-w7j9
Record: https://patchnext.com/advisories/cve-2026-52880 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/klever-io/klever-go 1.7.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/klever-io/klever-go: affected >= 1.7.14, <= 1.7.17; fixed in 1.7.18

## Suggested inspection (read-only)
- Go github.com/klever-io/klever-go: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/klever-io/klever-go.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-w4c6-7r69-w7j9 (GitHub-reviewed advisory GHSA-w4c6-7r69-w7j9 lists affected ranges: Go github.com/klever-io/klever-go >=1.7.14 <=1.7.17)

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