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CVE-2026-42349: Clerk JavaScript is the official JavaScript repository for Clerk authentication

32
Routine
HIGH 8.1UPGRADEUPGRADEUPGRADE

CVE-2026-42349 is a high-severity flaw (CVSS 8.1) affecting clerk\/astro, clerk\/backend, clerk\/chrome-extension. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Clerk JavaScript is the official JavaScript repository for Clerk authentication. has(), auth.protect(), and related authorization predicates in @clerk/shared, @clerk/nextjs, @clerk/backend, and other framework SDKs can return true for certain combined authorization checks when the result should be false, allowing a gated action to proceed for a user who does not satisfy the full set of requested conditions. This call shape can be bypassed if cert

Why this priority

  • High severity

A fixed release or distro patch exists.

Risk facts

CVSS score8.1 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.2% (top 84%)
CISA exploited listNo
WeaknessCWE-754, CWE-863
Published2026-05-11
Last modified2026-10-26
Publisher (CNA): GitHub, Inc. · Vendor: clerk

Share: LinkedIn · X · Reddit

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

clerk clerk\/astro UPGRADE
Affected: >= 2.0.0 and < 2.17.11 · >= 3.0.0 and < 3.0.18
Fixed in: 2.17.11, 3.0.18
Safe to downgrade to: a release before 2.0.0
1. Check installed version
npm ls clerkastro
2. UPGRADE to 2.17.11
npm install clerkastro@">=2.17.11"
3. If no update is available yet, DOWNGRADE to a release before 2.0.0
npm view clerkastro versions npm install clerkastro@"<2.0.0"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
clerk clerk\/backend UPGRADE
Affected: >= 2.0.0 and < 2.33.3 · >= 3.0.0 and < 3.2.14
Fixed in: 2.33.3, 3.2.14
Safe to downgrade to: a release before 2.0.0
1. Check installed version
npm ls clerkbackend
2. UPGRADE to 2.33.3
npm install clerkbackend@">=2.33.3"
3. If no update is available yet, DOWNGRADE to a release before 2.0.0
npm view clerkbackend versions npm install clerkbackend@"<2.0.0"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
clerk clerk\/chrome-extension UPGRADE
Affected: >= 1.3.5 and < 2.9.15 · >= 3.0.0 and < 3.1.15
Fixed in: 2.9.15, 3.1.15
Safe to downgrade to: a release before 1.3.5
1. Check installed version
npm ls clerkchrome-extension
2. UPGRADE to 2.9.15
npm install clerkchrome-extension@">=2.9.15"
3. If no update is available yet, DOWNGRADE to a release before 1.3.5
npm view clerkchrome-extension versions npm install clerkchrome-extension@"<1.3.5"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
clerk clerk\/clerk-expo UPGRADE
Affected: >= 2.2.11 and < 2.19.36
Fixed in: 2.19.36
Safe to downgrade to: a release before 2.2.11
1. Check installed version
npm ls clerkclerk-expo
2. UPGRADE to 2.19.36
npm install clerkclerk-expo@">=2.19.36"
3. If no update is available yet, DOWNGRADE to a release before 2.2.11
npm view clerkclerk-expo versions npm install clerkclerk-expo@"<2.2.11"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
clerk clerk\/clerk-js UPGRADE
Affected: >= 5.22.0 and < 5.125.10 · >= 6.0.0 and < 6.7.5
Fixed in: 5.125.10, 6.7.5
Safe to downgrade to: a release before 5.22.0
1. Check installed version
npm ls clerkclerk-js
2. UPGRADE to 5.125.10
npm install clerkclerk-js@">=5.125.10"
3. If no update is available yet, DOWNGRADE to a release before 5.22.0
npm view clerkclerk-js versions npm install clerkclerk-js@"<5.22.0"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
clerk clerk\/clerk-react UPGRADE
Affected: >= 5.9.0 and < 5.61.6
Fixed in: 5.61.6
Safe to downgrade to: a release before 5.9.0
1. Check installed version
npm ls clerkclerk-react
2. UPGRADE to 5.61.6
npm install clerkclerk-react@">=5.61.6"
3. If no update is available yet, DOWNGRADE to a release before 5.9.0
npm view clerkclerk-react versions npm install clerkclerk-react@"<5.9.0"
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42349?

clerk\/astro: upgrade to 2.17.11, 3.0.18; clerk\/backend: upgrade to 2.33.3, 3.2.14; clerk\/chrome-extension: upgrade to 2.9.15, 3.1.15. Exact commands for each OS are on this page.

Is CVE-2026-42349 being exploited?

CVE-2026-42349 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42349 affect?

CVE-2026-42349 affects clerk\/astro, clerk\/backend, clerk\/chrome-extension. Severity is high (CVSS 8.1). Clerk JavaScript is the official JavaScript repository for Clerk authentication. has(), auth.protect(), and related authorization predicates in @clerk/shared, @clerk/nextjs, @clerk/backend, and other framework SDKs can return true for certa

How urgent is CVE-2026-42349?

Priority 32/100. High severity

Software pages

React vulnerabilities · Google Chrome vulnerabilities

References

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