VulnerabilityPublished 1 Apr 2026

CVE-2026-34076: clerk javascript · Server-Side Request Forgery (SSRF)

Affects clerk javascriptSource CVE Database V5

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Not known to be exploited · CVSS 7.4 High · fixed in 0.1.5 : patch clerk javascript soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

7.4High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 25% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.1.5, 2.0.7, 3.2.3 +1

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
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 1 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
clerkjavascript	Affected @clerk/backend >= 3.0.0, < 3.2.3 – @clerk/hono >= 0.1.0, < 0.1.5 4 affected builds	Fixed in–
npm@clerk/hono`pkg:npm/@clerk/hono`Other threats	Affected <0.1.5	Fixed in 0.1.5
npm@clerk/express`pkg:npm/@clerk/express`Other threats	Affected <2.0.7	Fixed in 2.0.7
npm@clerk/backend`pkg:npm/@clerk/backend`Other threats	Affected <3.2.3	Fixed in 3.2.3
npm@clerk/fastify`pkg:npm/@clerk/fastify`Other threats	Affected <3.1.5	Fixed in 3.1.5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Immediate upgrade of all affected Clerk JavaScript packages to the patched versions: @clerk/hono to 0.1.5 or later, @clerk/express to 2.0.7 or later, @clerk/backend to 3.2.3 or later, and @clerk/fastify to 3.1.5 or later.
Review and rotate Clerk-Secret-Keys used in affected applications to invalidate any potentially compromised keys.
Implement strict network egress controls and monitoring to detect and block unauthorized outbound requests that could indicate SSRF exploitation attempts.
Employ runtime application self-protection (RASP) or web application firewalls (WAF) with rules targeting SSRF patterns and anomalous proxy requests.
Conduct thorough code audits and penetration testing focusing on SSRF and proxy-related functionalities in authentication flows.
Educate development teams on secure coding practices to avoid proxy misuse and validate all incoming request paths rigorously.
8. Use environment segmentation and least privilege principles to limit the impact scope if a secret key is compromised.

Description

Clerk JavaScript is the official JavaScript repository for Clerk authentication. In @clerk/hono from versions 0.1.0 to before 0.1.5, @clerk/express from versions 2.0.0 to before 2.0.7, @clerk/backend from versions 3.0.0 to before 3.2.3, and @clerk/fastify from versions 3.1.0 to before 3.1.5, the clerkFrontendApiProxy function in @clerk/backend is vulnerable to Server-Side Request Forgery (SSRF). An unauthenticated attacker can craft a request path that causes the proxy to send the application's Clerk-Secret-Key to an attacker-controlled server. This issue has been patched in @clerk/hono version 0.1.5, @clerk/express version 2.0.7, @clerk/backend version 3.2.3, and @clerk/fastify version 3.1.5.

Impact

The primary impact of this vulnerability is the unauthorized disclosure of the Clerk-Secret-Key, a sensitive credential that underpins authentication and session management in applications using Clerk JavaScript libraries. If an attacker obtains this secret key, they can potentially impersonate legitimate users, escalate privileges, or manipulate authentication flows, leading to data breaches, unauthorized access to user accounts, and compromise of application integrity. The confidentiality of user data and authentication tokens is at significant risk. Although availability is not directly impacted, the integrity and confidentiality breaches can cause severe reputational damage, regulatory penalties, and loss of user trust. Organizations relying on Clerk for authentication, especially those with high-value or sensitive data, face increased risk of targeted attacks. The vulnerability's network-based exploitation and lack of required authentication mean attackers can attempt exploitation remotely, increasing the threat surface. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the potential for future attacks, especially as the vulnerability is publicly documented.

CWE-918Server-Side Request Forgery (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Implementation · Operation
If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Operation
If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/clerk/javascript/security/advisories/GHSA-gjxx-92w9-8v8f (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 Apr 2026, 18:53 UTC

WeaknessesCWE-918

Technical details

References

Community reviews

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