CVE-2026-44511: katalyst-koi Session Cookies Can Be Replayed Vulnerability

HIGH
Advisory Identifier: GHSA-4cx3-3c38-j9vv
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CVSS 7.4
CWE-613
Published
Advisory Summary

CVE-2026-44511 is a HIGH (CVSS 7.4) session cookies can be replayed vulnerability (CWE-613: Insufficient Session Expiration) affecting katalyst-koi libraries in the RubyGems ecosystem. The issue involves session cookies can be replayed after user logout. Remediation is available by upgrading affected packages to version 4.20.0, 5.6.0.

CVE-2026-44511 at a Glance

CVE Identifier CVE-2026-44511
GHSA Identifier GHSA-4cx3-3c38-j9vv
Severity HIGH
CVSS v3.1 Base Score 7.4
CWE Classification CWE-613: Insufficient Session Expiration
Affected Product katalyst-koi
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 7.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-44511

To remediate this vulnerability, upgrade all affected katalyst-koi dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

katalyst-koi fixed: 4.20.0 
Upgrade katalyst-koi to 4.20.0
katalyst-koi fixed: 5.6.0 
Upgrade katalyst-koi to 5.6.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for katalyst-koi

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-44511, inspect your project dependencies for katalyst-koi:

inspect dependencies for katalyst-koi

Analyze the terminal output to locate any version of katalyst-koi in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.20.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-613: Insufficient Session Expiration, where according to wasc, "insufficient session expiration is when a web site permits an attacker to reuse old session credentials or session ids for authorization.". In katalyst-koi, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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

CVE-2026-44511 Affected katalyst-koi Versions

2 component(s)
Fixed Versions:
4.20.05.6.0
Product / Package Ecosystem Affected Versions Fixed Version
katalyst-koi
gem/katalyst-koi
RubyGems
< 4.20.0
4.20.0
katalyst-koi
gem/katalyst-koi
RubyGems
≥ 5.0.0
< 5.6.0
5.6.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/katalyst/koi/security/advisories/GHSA-4cx3-3c38-j9vv
NVD — CVE-2026-44511 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44511
katalyst-koi Source Repository REPOSITORY
https://github.com/katalyst/koi
katalyst-koi Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/katalyst-koi/CVE-2026-44511.yml
katalyst-koi Security Information SECURITY
https://guides.rubyonrails.org/v5.2.0/security.html#replay-attacks-for-cookiestore-sessions

Frequently Asked Questions

What is CVE-2026-44511?
CVE-2026-44511 is a security vulnerability in katalyst-koi involving Session cookies can be replayed after user logout under CWE-613: Insufficient Session Expiration.
Which katalyst-koi versions are affected?
Affected versions include releases prior to 4.20.0, 5.6.0 across affected packages: katalyst-koi.
What version fixes CVE-2026-44511?
Upgrading to 4.20.0, 5.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is katalyst-koi affected?
Yes, katalyst-koi is affected in releases prior to 4.20.0, 5.6.0. Upgrade your dependency to 4.20.0, 5.6.0 or later.
What is the CVSS score of CVE-2026-44511?
CVE-2026-44511 has a CVSS v3.1 base score of 7.4 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-44511?
CVE-2026-44511 is classified under CWE-613: Insufficient Session Expiration (According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization.").
How can I check RubyGems dependencies for CVE-2026-44511?
Run the dependency tree command: 'inspect dependencies for katalyst-koi'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4cx3-3c38-j9vv",
  "modified" : "2026-05-29T21:45:23Z",
  "published" : "2026-05-07T02:13:42Z",
  "aliases" : [ "CVE-2026-44511" ],
  "summary" : "katalyst-koi: Session cookies can be replayed after user logout",
  "details" : "### Impact\n\nAdmin 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.\n\nThis affects applications using Koi admin authentication where an admin session cookie may have been exposed, cached, intercepted, or otherwise retained after logout.\n\n### Patches\n\nThe issue has been patched by recording admin logout time and rejecting any admin session cookie created before the user’s most recent logout.\n\nUsers should upgrade to the patched Koi releases once available.\n\n### Workarounds\n\nKatalyst Koi recommends upgrading to the latest available version, or back porting the changes released in 5.6.0/4.20.0\n\n### Resources\n\nThis is an application of https://guides.rubyonrails.org/v5.2.0/security.html#replay-attacks-for-cookiestore-sessions",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "katalyst-koi"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.20.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "katalyst-koi"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/katalyst/koi/security/advisories/GHSA-4cx3-3c38-j9vv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44511"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/katalyst/koi"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/katalyst-koi/CVE-2026-44511.yml"
  }, {
    "type" : "WEB",
    "url" : "https://guides.rubyonrails.org/v5.2.0/security.html#replay-attacks-for-cookiestore-sessions"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-613" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-07T02:13:42Z",
    "nvd_published_at" : "2026-05-14T17:16:22Z"
  }
}