emp3r0r has an unauthenticated HTTP Polling DoS

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-2026-61554: 0.71% estimated exploitation activity in the next 30 days; percentile 53.50 (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 httppoll C2 transport accepts attacker-controlled HTTP polling sessions before CBOR MsgAuth authentication is completed. A remote unauthenticated attacker can create arbitrary polling sessions and send request bodies that are forwarded into the C2 dispatch path. This can consume server resources and trigger pre-auth C2 processing. Details The plain HTTP C2 server starts the HTTP polling listener and forwards requests into HandleHTTPServerSession: The HTTP polling handler accepts an attacker-supplied sessionID and init=1 cookie, then creates and stores a server-side stream before authentication: POST bodies for that unauthenticated session are read and queued before CBOR authentication rejects them: Authentication only happens later in the C2 dispatch layer: PoC 1. Start the C2 server in a lab environment with the HTTP polling transport exposed, for example with --http-port 12345. 2. Send an unauthenticated HTTP POST to the default polling path /api/v1/telemetry with a…

Published by the source

15 Sep 2026, 20:47 UTC

Last modified by the source

28 Sep 2026, 17:00 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4595-rvpx-4q34

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6487

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4595-rvpx-4q34

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# Patch Next advisory brief: CVE-2026-61554

Advisory: emp3r0r has an unauthenticated HTTP Polling DoS
IDs: CVE-2026-61554, GHSA-4595-rvpx-4q34
Record: https://patchnext.com/advisories/cve-2026-61554 (revision 3, source checked 26 Oct 2026, 15:29 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/jm33-m0/emp3r0r/core 0.0.0-20260531142011-aed3d81641ab. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/jm33-m0/emp3r0r/core: affected < 0.0.0-20260531142011-aed3d81641ab; fixed in 0.0.0-20260531142011-aed3d81641ab

## Suggested inspection (read-only)
- Go github.com/jm33-m0/emp3r0r/core: 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/jm33-m0/emp3r0r/core.
- 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://osv.dev/vulnerability/GHSA-4595-rvpx-4q34 (OSV record GHSA-4595-rvpx-4q34 lists affected ranges: Go github.com/jm33-m0/emp3r0r/core >=0 <0.0.0-20260531142011-aed3d81641ab (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6487 (OSV record GO-2026-6487 lists affected ranges: Go github.com/jm33-m0/emp3r0r/core >=0 <0.0.0-20260531142011-aed3d81641ab (fixed))
- Verified: https://github.com/advisories/GHSA-4595-rvpx-4q34 (GitHub-reviewed advisory GHSA-4595-rvpx-4q34 lists affected ranges: Go github.com/jm33-m0/emp3r0r/core >=0 <0.0.0-20260531142011-aed3d81641ab)

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