CVE-2025-53548VulnerabilityPublished 9 Jul 2025

CVE-2025-53548: clerk javascript · Insufficient Verification of Data Authenticity

Affects clerk javascriptSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 2.4.0 soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.4.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade clerk javascript to 2.4.0.

Affected software

Product	Affected	Fixed in
clerk javascript	Affected <2.4.0	Fixed in 2.4.0

AI-suggested

European organizations should immediately verify if their applications use Clerk JavaScript versions prior to 2.4.0 and upgrade to version 2.4.0 or later to apply the official fix. Beyond upgrading, developers should implement additional webhook security measures such as: 1) Independently validating webhook signatures using cryptographic methods and secrets outside of the Clerk library to add defense in depth. 2) Employing strict input validation and sanitization on webhook payloads to prevent injection attacks. 3) Implementing logging and monitoring of webhook events to detect anomalies or unexpected patterns indicative of exploitation attempts. 4) Restricting webhook endpoints to accept requests only from Clerk's known IP ranges or using network-level controls like firewall rules. 5) Conducting regular security audits and penetration testing focused on webhook handling components. 6) Educating development teams on secure webhook processing best practices to avoid similar issues. These measures help reduce risk even if future vulnerabilities arise.

Description

Clerk helps developers build user management. Applications that use the verifyWebhook() helper to verify incoming Clerk webhooks are susceptible to accepting improperly signed webhook events. The issue was resolved in @clerk/backend 2.4.0.

Impact

For European organizations using Clerk's JavaScript library for user management and webhook processing, this vulnerability poses a serious risk to data integrity. Attackers could send forged webhook events that the application accepts as genuine, potentially leading to unauthorized actions such as user account manipulation, privilege escalation, or triggering unintended workflows. This could disrupt business processes, compromise user data integrity, and damage trust in affected services. Since the vulnerability does not impact confidentiality or availability directly, the primary concern is unauthorized data modification and the downstream effects on application logic and security. Organizations in sectors with strict regulatory requirements around data integrity and user authentication—such as finance, healthcare, and government—may face compliance risks if exploited. The lack of required authentication or user interaction for exploitation increases the threat level, making automated attacks feasible. Given the widespread adoption of JavaScript-based user management tools and the growing reliance on webhook integrations, the potential attack surface is significant within Europe.

CWE-345Insufficient Verification of Data Authenticity (opens in a new tab)
Class weaknessOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Spoofing of UDDI/ebXML Messages (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/clerk/javascript/security/advisories/GHSA-9mp4-77wg-rwx9 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Jul 2025, 17:39 UTC

WeaknessesCWE-345

Technical details

References

Community reviews

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