pac4j-core affected by a Java deserialization vulnerability
pac4j is a security framework for Java. pac4j-core prior to version 4.0.0 is affected by a Java deserialization vulnerability. The vulnerability affects systems that store externally controlled values in attributes of the UserProfile class from pac4j-core. It can be exploited by providing an attribute that contains a serialized Java object with a special prefix {#sb64} and Base64 encoding. This issue may lead to Remote Code Execution (RCE) in the worst case. Although a RestrictedObjectInputStream is in place, that puts some restriction on what classes can be deserialized, it still allows a broad range of java packages and potentially exploitable with different gadget chains. pac4j versions 4.0.0 and greater are not affected by this issue. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.pac4j:pac4j-core | < 4.0.0 | 4.0.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2023-25581
- https://github.com/frohoff/ysoserial
- https://github.com/pac4j/pac4j
- https://github.com/pac4j/pac4j/blob/5834aeb22ad3a4369dfa572be60d7b20f5784a8f/pac4j-core/src/main/java/org/pac4j/core/profile/InternalAttributeHandler.java#L95
- https://portswigger.net/web-security/deserialization
- https://securitylab.github.com/advisories
- https://securitylab.github.com/advisories/GHSL-2022-085_pac4j
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-502- Platform
- Java / Kotlin (Maven)
- Package
org.pac4j:pac4j-core- Disclosed
- 11.10.2024
- Updated
- 11.10.2026 12:21
Sources and licenses
OSV / GitHub Advisory Database - GHSA-76mw-6p95-x9x5 - CC BY 4.0
Vulnerability history: org.pac4j:pac4j-core
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 10.2024 04.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
Disclosures per year
- 2024: 1
- 2025: 0
- 2026: 1
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pac4j-core affected by a Java deserialization vulnerability this entry
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