Rancher Login Parameter Can Be Edited

Exploitation

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

CVSS

4.7 · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

EPSS

• CVE-2019-11881: 1.97% estimated exploitation activity in the next 30 days; percentile 80.42 (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.

A vulnerability exists in Rancher 2.1.4 in the login component, where the errorMsg parameter can be tampered to display arbitrary content, filtering tags but not special characters or symbols. There's no other limitation of the message, allowing malicious users to lure legitimate users to visit phishing sites with scare tactics, e.g., displaying a "This version of Rancher is outdated, please visit https://malicious.rancher.site/upgrading" message. PoC 1. Access the following endpoint on any Rancher instance up to 2.1.4: https://RANCHER:PORT/login?errorMsg=%68%74%74%70%73%3a%2f%2f%77%77%77%2e%6f%77%61%73%70%2e%6f%72%67%2f%69%6e%64%65%78%2e%70%68%70%2f%57%65%62%5f%50%61%72%61%6d%65%74%65%72%5f%54%61%6d%70%65%72%69%6e%67 It will display a link to OWASP Wiki explaining Web Parameter Tampering.

Published by the source

24 May 2022, 16:47 UTC

Last modified by the source

4 Dec 2024, 16:23 UTC

Source last checked

26 Oct 2026, 15:08 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-2p4g-jrmx-r34m

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# Patch Next advisory brief: CVE-2019-11881

Advisory: Rancher Login Parameter Can Be Edited
IDs: CVE-2019-11881, GHSA-2p4g-jrmx-r34m
Record: https://patchnext.com/advisories/cve-2019-11881 (revision 1, source checked 26 Oct 2026, 15:08 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rancher/rancher: affected <= 2.1.4

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/rancher/rancher.
- 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-2p4g-jrmx-r34m (GitHub-reviewed advisory GHSA-2p4g-jrmx-r34m lists affected ranges: Go github.com/rancher/rancher >=0 <=2.1.4)

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