How severe is CVE-2023-25581?

No CVSS score has been assigned to CVE-2023-25581 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2023-25581?

CVE-2023-25581 affects the following packages: org.pac4j:pac4j-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2023-25581?

Update org.pac4j:pac4j-core to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-25581 is resolved across your whole dependency graph.

How do I detect CVE-2023-25581 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.pac4j:pac4j-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2023-25581 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2023-25581?

O3 pinpoints whether CVE-2023-25581 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2023-25581 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-25581 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-25581?

CVE-2023-25581 has an EPSS (Exploit Prediction Scoring System) score of 1.9%, placing it in the 78th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2023-25581 published, and has it been updated?

CVE-2023-25581 was published on October 10, 2024 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

CVE-2023-25581

Deserialization of untrusted data in InternalAttributeHandler in pac4j

Also known asGHSA-76mw-6p95-x9x5

Published

Oct 10, 2024

Updated

Apr 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

1.9%probability of exploitation in next 30 days

Lower Risk78th percentile-17.08%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

☕org.pac4j:pac4j-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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 Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.pac4j:pac4j-core`	all versions	4.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.pac4j:pac4j-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.pac4j:pac4j-core to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-25581 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-25581 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2023-25581. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 allo

O3 Security · Impact-Aware SCA

Is CVE-2023-25581 in your dependencies?

O3 detects CVE-2023-25581 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works