Vulnerability in @clerk/shared (CVE-2026-42349)
Summary
Vulnerability in @clerk/shared (CVE-2026-42349). Confidential information can be exposed externally. Exploitable via clerkMiddleware. Mitigation: upgrade to 4.8.3 or later.
Original description
The description as published by the source.
Summary
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.
Sessions are not compromised and no existing user can be impersonated. The bypass is limited to the authorization decision returned by the predicate. clerkMiddleware continues to authenticate requests correctly, auth() reflects the real authentication state, and token verification is unaffected.
Who is affected
All apps that combine more than one authorization dimension in a single has() or auth.protect() call should upgrade to the patched versions. Patches are drop-in with no API changes. The information below describes the scope of the bypass and helps developers understand whether their apps are potentially affected, but is not a reason to delay the upgrade.
This call shape can be bypassed if certain conditions are met: a has() or auth.protect() call that combines a reverification check with any of role, permission, feature, or plan, or that combines a billing check (feature or plan) with a role or permission check.
// Reverification combined with role / permission / feature / plan
await auth.protect({ permission: 'org:settings:delete', reverification: 'strict' });
const canAct = has({…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42349 has been found in @clerk/shared.
Attackers can target a specific entry point like clerkMiddleware over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade @clerk/shared to 4.8.3 or later.
If unsure, ask your IT team or search "@clerk/shared CVE-2026-42349" on the vendor's site.
CVE-2026-42349 (@clerk/shared) — CWE-754 / CVSS v3 8.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: clerkMiddleware / reverification / role / permission
Patched: 4.8.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-754) exists in @clerk/shared. Attackers reach the vulnerable code path via clerkMiddleware.
Check the vendor advisory for the affected versions of @clerk/shared. Attack surface: clerkMiddleware / reverification / role / permission.
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.
Update to 4.8.3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@clerk/shared' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r '@clerk/shared' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
@clerk/sharedを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade @clerk/shared to 4.8.3ステージング環境で 4.8.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com