October CMS Session ID not invalidated after logout

Exploitation

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

CVSS

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

EPSS

• CVE-2021-3311: 2.94% estimated exploitation activity in the next 30 days; percentile 87.13 (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.

Impact When logging out, the session ID was not invalidated. This is not a problem while the user is logged out, but as soon as the user logs back in the old session ID would be valid again; which means that anyone that gained access to the old session cookie would be able to act as the logged in user. This is not a major concern for the majority of cases, since it requires a malicious party gaining access to the session cookie in the first place, but nevertheless has been fixed. Patches Issue has been patched in Build 472 (v1.0.472) and v1.1.2. Workarounds Apply https://github.com/octobercms/library/commit/642f597489e6f644d4bd9a0c267e864cabead024 to your installation manually if unable to upgrade to Build 472 or v1.1.2. References - Reported by Anisio (Brazilian Information Security Analyst) - http://cve.circl.lu/cve/CVE-2021-3311 For more information If you have any questions or comments about this advisory: Email us at hello@octobercms.com Threat assessment: <img width="699"…

Published by the source

10 Feb 2021, 02:32 UTC

Last modified by the source

7 Sep 2023, 17:47 UTC

Source last checked

26 Oct 2026, 14:09 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7ggw-h8pp-r95r

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2021-3311

Advisory: October CMS Session ID not invalidated after logout
IDs: CVE-2021-3311, GHSA-7ggw-h8pp-r95r
Record: https://patchnext.com/advisories/cve-2021-3311 (revision 1, source checked 26 Oct 2026, 14:09 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: october/rain 1.1.2, 1.0.472. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist october/rain: affected < 1.0.472; >= 1.1.0, < 1.1.2; fixed in 1.1.2, 1.0.472

## Suggested inspection (read-only)
- Packagist october/rain: 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 october/rain.
- 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-7ggw-h8pp-r95r (GitHub-reviewed advisory GHSA-7ggw-h8pp-r95r lists affected ranges: Packagist october/rain >=0 =1.1.0 <1.1.2)

Commands are suggestions: review each one before running it.