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CWE-323Weakness · CWE-323

CVE-2026-59099

CRITICAL · 9.1 CVSS v3.1 Published 2026-07-02
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Apereo CAS 7.3.0 before 8.0.0-RC6 contains a cryptographic vulnerability that allows remote unauthenticated attackers to recover plaintext conversation state by exploiting AES-GCM initialization vector reuse across the server lifetime. Attackers can collect multiple client-side webflow execution tokens from the unauthenticated login page and perform known-plaintext analysis to decrypt the webflow conversation state due to keystream reuse caused by a fixed all-zero IV paired with the same encryption key.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Apereo CAS versions 7.3.0 before 8.0.0-RC6 use a fixed all-zero initialization vector (IV) with AES-GCM encryption for webflow conversation state. Since the same IV is reused across the server lifetime with a static encryption key, attackers can collect multiple webflow execution tokens from the unauthenticated login page and perform known-plaintext cryptanalysis to recover plaintext conversation state due to keystream reuse.

MitigationUpgrade to Apereo CAS 8.0.0-RC6 or later which implements proper per-message IV generation, or apply vendor-supplied cryptographic patch to enable unique IV handling.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Apereo CAS version
    Check the deployed CAS version from the WAR file, build configuration, or runtime logs. Common locations: pom.xml dependency version, build.gradle dependencies, or the CAS management dashboard.
    Affected if Version is 7.3.0, 7.3.1, 7.3.2, 7.3.3, 7.3.4, 7.3.5, 7.3.6, 7.3.7, 7.3.8, 7.3.9, 7.3.10, 7.3.11, 8.0.0-RC1, 8.0.0-RC2, 8.0.0-RC3, 8.0.0-RC4, or 8.0.0-RC5
  2. Verify client-side token storage is enabled
    Inspect the CAS configuration for webflow state storage. Look for settings like 'cas.webflow.crypto.enabled=true' or 'cas.webflow.state=CLIENT' in the cas.properties or application.yml file.
    Affected if Client-side token storage for webflow conversation state is enabled in the CAS configuration
  3. Check AES-GCM encryption configuration
    Review the encryption settings for webflow tokens. Look for 'cas.webflow.crypto.encryption=AESGCM' or similar AES-GCM configuration in the CAS properties file.
    Affected if AES-GCM encryption is configured for webflow conversation state tokens

You are affected if the installed CAS version is between 7.3.0 and 8.0.0-RC5 and client-side token storage with AES-GCM encryption is enabled for webflow state.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Interim mitigation

Upgrade to Apereo CAS 8.0.0-RC6 or later which implements proper per-message IV generation, or apply vendor-supplied cryptographic patch to enable unique IV handling.

Recommended fix High confidence

Apereo CAS 8.0.0-RC6 or later

  1. 1. Identify the current Apereo CAS version in use by checking the CAS WAR file or deployment configuration
  2. 2. Download CAS version 8.0.0-RC6 or a later stable release from the official Apereo CAS releases repository
  3. 3. Review the release notes for version 8.0.0-RC6 and subsequent releases to understand any configuration or behavioral changes
  4. 4. Backup the existing CAS deployment including configuration files and any custom modifications
  5. 5. Deploy the new CAS 8.0.0-RC6 or later WAR file to the application server
  6. 6. Verify that the AES-GCM encryption now uses a non-static initialization vector (IV) for each encryption operation
  7. 7. Test the authentication flow and webflow conversation state encryption/decryption to confirm proper operation
  8. 8. Monitor logs for any encryption-related errors or warnings
Caveat Review release notes for version 8.x as there may be configuration schema changes or deprecated features compared to 7.x

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-59099 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data