What is CVE-2025-53548?

CVE-2025-53548 is a high-severity security vulnerability in @clerk/backend (npm), affecting versions >= 2.0.0, < 2.4.0. It is fixed in 2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3.

How severe is CVE-2025-53548?

CVE-2025-53548 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which packages are affected by CVE-2025-53548?

@clerk/backend (npm) versions >= 2.0.0, = 2.9.0, = 1.6.0, = 2.3.0, = 6.2.10, = 1.7.0, = 1.5.0, = 4.8.0, = 0.16.0, < 0.18.3.

Is there a fix for CVE-2025-53548?

Yes. CVE-2025-53548 is fixed in 2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3. Upgrade to this version or later.

Is CVE-2025-53548 exploitable, and should I be worried?

Whether CVE-2025-53548 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2025-53548 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2025-53548?

Upgrade: @clerk/backend to 2.4.0 or later, @clerk/astro to 2.10.2 or later, @clerk/express to 1.7.4 or later, @clerk/fastify to 2.4.4 or later, @clerk/nextjs to 6.23.3 or later, @clerk/nuxt to 1.7.5 or later, @clerk/react-router to 1.6.4 or later, @clerk/remix to 4.8.5 or later, @clerk/tanstack-react-start to 0.18.3 or later.

CVE-2025-53548 in @clerk/backend | Intelligent Application Security

Q: How severe is CVE-2025-53548?

CVE-2025-53548 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which packages are affected by CVE-2025-53548?

@clerk/backend (npm) versions >= 2.0.0, = 2.9.0, = 1.6.0, = 2.3.0, = 6.2.10, = 1.7.0, = 1.5.0, = 4.8.0, = 0.16.0, < 0.18.3.

Q: Is there a fix for CVE-2025-53548?

Yes. CVE-2025-53548 is fixed in 2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3. Upgrade to this version or later.

Q: Is CVE-2025-53548 exploitable, and should I be worried?

Whether CVE-2025-53548 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2025-53548 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2025-53548?

Upgrade: @clerk/backend to 2.4.0 or later, @clerk/astro to 2.10.2 or later, @clerk/express to 1.7.4 or later, @clerk/fastify to 2.4.4 or later, @clerk/nextjs to 6.23.3 or later, @clerk/nuxt to 1.7.5 or later, @clerk/react-router to 1.6.4 or later, @clerk/remix to 4.8.5 or later, @clerk/tanstack-react-start to 0.18.3 or later.

Summary

Resolution

The issue was resolved in @clerk/backend 2.4.0 by:

Properly parsing the webhook request's signatures and comparing them against the signature generated from the received event

Workarounds

If unable to upgrade, developers can workaround this issue by verifying webhooks manually, per this documentation.

Impact

Applications that use the verifyWebhook() helper to verify incoming Clerk webhooks are susceptible to accepting improperly signed webhook events.

CVE-2025-53548 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3); upgrading removes the vulnerable code path.

Affected versions

@clerk/backend (>= 2.0.0, < 2.4.0) @clerk/astro (>= 2.9.0, < 2.10.2) @clerk/express (>= 1.6.0, < 1.7.4) @clerk/fastify (>= 2.3.0, < 2.4.4) @clerk/nextjs (>= 6.2.10, < 6.23.3) @clerk/nuxt (>= 1.7.0, < 1.7.5) @clerk/react-router (>= 1.5.0, < 1.6.4) @clerk/remix (>= 4.8.0, < 4.8.5) @clerk/tanstack-react-start (>= 0.16.0, < 0.18.3)

Security releases

@clerk/backend → 2.4.0 (npm) @clerk/astro → 2.10.2 (npm) @clerk/express → 1.7.4 (npm) @clerk/fastify → 2.4.4 (npm) @clerk/nextjs → 6.23.3 (npm) @clerk/nuxt → 1.7.5 (npm) @clerk/react-router → 1.6.4 (npm) @clerk/remix → 4.8.5 (npm) @clerk/tanstack-react-start → 0.18.3 (npm)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

See it in your environment

Remediation advice

@clerk/backend: the helper has been patched as of 2.4.0
@clerk/astro: the helper has been patched as of 2.10.2
@clerk/express: the helper has been patched as of 1.7.4
@clerk/fastify: the helper has been patched as of 2.4.4
@clerk/nextjs: the helper has been patched as of 6.23.3
@clerk/nuxt: the helper has been patched as of 1.7.5
@clerk/react-router: the helper has been patched as of 1.6.4
@clerk/remix: the helper has been patched as of 4.8.5
@clerk/tanstack-react-start: the helper has been patched as of 0.18.3

Frequently Asked Questions

What is CVE-2025-53548? CVE-2025-53548 is a high-severity security vulnerability in @clerk/backend (npm), affecting versions >= 2.0.0, < 2.4.0. It is fixed in 2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3.
How severe is CVE-2025-53548? CVE-2025-53548 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which packages are affected by CVE-2025-53548?
- @clerk/backend (npm) (versions >= 2.0.0, < 2.4.0)
- @clerk/astro (npm) (versions >= 2.9.0, < 2.10.2)
- @clerk/express (npm) (versions >= 1.6.0, < 1.7.4)
- @clerk/fastify (npm) (versions >= 2.3.0, < 2.4.4)
- @clerk/nextjs (npm) (versions >= 6.2.10, < 6.23.3)
- @clerk/nuxt (npm) (versions >= 1.7.0, < 1.7.5)
- @clerk/react-router (npm) (versions >= 1.5.0, < 1.6.4)
- @clerk/remix (npm) (versions >= 4.8.0, < 4.8.5)
- @clerk/tanstack-react-start (npm) (versions >= 0.16.0, < 0.18.3)
Is there a fix for CVE-2025-53548? Yes. CVE-2025-53548 is fixed in 2.4.0, 2.10.2, 1.7.4, 2.4.4, 6.23.3, 1.7.5, 1.6.4, 4.8.5, 0.18.3. Upgrade to this version or later.
Is CVE-2025-53548 exploitable, and should I be worried? Whether CVE-2025-53548 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2025-53548 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2025-53548?
- Upgrade @clerk/backend to 2.4.0 or later
- Upgrade @clerk/astro to 2.10.2 or later
- Upgrade @clerk/express to 1.7.4 or later
- Upgrade @clerk/fastify to 2.4.4 or later
- Upgrade @clerk/nextjs to 6.23.3 or later
- Upgrade @clerk/nuxt to 1.7.5 or later
- Upgrade @clerk/react-router to 1.6.4 or later
- Upgrade @clerk/remix to 4.8.5 or later
- Upgrade @clerk/tanstack-react-start to 0.18.3 or later

Other vulnerabilities in @clerk/backend

CVE-2026-42349 CVE-2025-53548