CVE-2026-40458
Cross-Site Request Forgery in PAC4J
Description
PAC4J is vulnerable to Cross-Site Request Forgery (CSRF). A malicious attacker can craft a specially designed website which, when visited by a user, will automatically submit a forged cross-site request with a token whose hash collides with the victim's legitimate CSRF token. Importantly, the attacker does not need to know the victim’s CSRF token or its hash prior to the attack. Collisions in the deterministic String.hashCode() function can be computed directly, reducing the effective token's security space to 32 bits. This bypasses CSRF protection, allowing profile updates, password changes, account linking, and any other state-changing operations to be performed without the victim's consent. This issue was fixed in PAC4J versions 5.7.10 and 6.4.1
INFO
Published Date :
April 17, 2026, 2:16 p.m.
Last Modified :
April 17, 2026, 3:38 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-40458
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | 4bb8329e-dd38-46c1-aafb-9bf32bcb93c6 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update PAC4J to version 5.7.10 or later.
- Update PAC4J to version 6.4.1 or later.
- Implement secure CSRF token generation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-40458.
| URL | Resource |
|---|---|
| https://cert.pl/en/posts/2026/04/CVE-2026-40458/ | |
| https://www.pac4j.org/blog/security-advisory-pac4j-core-and-ldap.html |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-40458 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-40458
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-40458 vulnerability anywhere in the article.
-
cert.pl
Vulnerabilities in PAC4J software
Vulnerabilities in PAC4J software CVE ID CVE-2026-40458 Publication date 17 April 2026 Vendor PAC4J Product PAC4J Vulnerable versions From 5.0 to 5.7.10 From 6.0 to 6.4.1 Vulnerability type (CWE) Cros ... Read more
The following table lists the changes that have been made to the
CVE-2026-40458 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Apr. 17, 2026
Action Type Old Value New Value Added Description PAC4J is vulnerable to Cross-Site Request Forgery (CSRF). A malicious attacker can craft a specially designed website which, when visited by a user, will automatically submit a forged cross-site request with a token whose hash collides with the victim's legitimate CSRF token. Importantly, the attacker does not need to know the victim’s CSRF token or its hash prior to the attack. Collisions in the deterministic String.hashCode() function can be computed directly, reducing the effective token's security space to 32 bits. This bypasses CSRF protection, allowing profile updates, password changes, account linking, and any other state-changing operations to be performed without the victim's consent. This issue was fixed in PAC4J versions 5.7.10 and 6.4.1 Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-352 Added Reference https://cert.pl/en/posts/2026/04/CVE-2026-40458/ Added Reference https://www.pac4j.org/blog/security-advisory-pac4j-core-and-ldap.html