CVE-2026-44511 — katalyst-koi
HIGHCVE-2026-44511 is a high-severity (CVSS 7.4) CWE-613 vulnerability in katalyst-koi. A fix is available for katalyst-koi — see the affected versions and patch details below.
Katalyst Koi: Session cookies can be replayed after user logout
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44511.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
katalyst-koi💎katalyst-koiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Admin session cookies were not invalidated when an admin user logged out. An attacker with access to a valid admin session cookie could continue to access admin functionality after logout, until the cookie expired or session secrets were rotated.
This affects applications using Koi admin authentication where an admin session cookie may have been exposed, cached, intercepted, or otherwise retained after logout.
Patches
The issue has been patched by recording admin logout time and rejecting any admin session cookie created before the user’s most recent logout.
Users should upgrade to the patched Koi releases once available.
Workarounds
Katalyst Koi recommends upgrading to the latest available version, or back porting the changes released in 5.6.0/4.20.0
Resources
This is an application of https://guides.rubyonrails.org/v5.2.0/security.html#replay-attacks-for-cookiestore-sessions
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | katalyst-koi | all versions | 4.20.0bundle update katalyst-koi --conservative |
| 💎RubyGems | katalyst-koi | ≥ 5.0.0&&< 5.6.0 | 5.6.0bundle update katalyst-koi --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for katalyst-koi, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update katalyst-koi to 4.20.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44511 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2026-44511 in your dependencies?
Find it across RubyGems, including transitive dependencies.