CVE-2026-40458Network attack vector

Account changes via colliding CSRF token hashes

Published Apr 17, 2026 · Updated Apr 17, 2026

Cross-site request forgery in pac4j 5.x before 5.7.10 and 6.x before 6.4.1 allows attackers to alter accounts via forged requests. The pac4j-core CSRF support relies on deterministic String.hashCode() output, allowing a computed 32-bit collision to validate a forged token. A victim must visit attacker-controlled content while authenticated; forged requests can update profiles, change passwords, link accounts, or invoke other exposed state changes.

CVSS severity7.0
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site request forgery in pac4j 5.x before 5.7.10 and 6.x before 6.4.1 allows attackers to alter accounts via forged requests. The pac4j-core CSRF support relies on deterministic String.hashCode() output, allowing a computed 32-bit collision to validate a forged token. A victim must visit attacker-controlled content while authenticated; forged requests can update profiles, change passwords, link accounts, or invoke other exposed state changes.

The record

CVE
CVE-2026-40458
Published
Apr 17, 2026
Updated
Apr 17, 2026
Vendor
pac4j
Product
pac4j
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.0 <5.7.10
  2. Affected versionversion=6.0 <6.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

pac4j · pac4jversion=5.0 <5.7.10; version=6.0 <6.4.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
7.0CERT.PLCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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