astro: Interpretation Conflict
CVE-2026-41248 is a critical-severity interpretation conflict vulnerability in astro from Clerk, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected astro versions: >= 0.0.1, < 1.5.7; >= 2.0.0-snapshot.v20241206174604, <= 2.17.9; >= 3.0.0, < 3.0.15. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.32% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of astro you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Clerk | astro | >= 0.0.1, < 1.5.7; >= 2.0.0-snapshot.v20241206174604, <= 2.17.9; >= 3.0.0, < 3.0.15 | Not stated |
| Clerk | nextjs | >= 5.0.0, < 5.7.6; >= 6.0.0-snapshot.vb87a27f, < 6.39.2; >= 7.0.0, < 7.2.1 | Not stated |
| Clerk | nuxt | >= 1.1.0, < 1.13.28; >= 2.0.0, < 2.2.2 | Not stated |
| Clerk | shared | >= 2.20.17, < 2.22.1; >= 3.0.0-canary.v20250225091530, < 3.47.4; >= 4.0.0, < 4.8.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (github.com).
Official description
Clerk JavaScript is the official JavaScript repository for Clerk authentication. createRouteMatcher in @clerk/nextjs, @clerk/nuxt, and @clerk/astro can be bypassed by certain crafted requests, allowing them to skip middleware gating and reach downstream handlers. This vulnerability is fixed in @clerk/astro 1.5.7, 2.17.10, and 3.0.15; @clerk/nextjs 5.7.6, 6.39.2, and 7.2.1; @clerk/nuxt 1.13.28 and 2.2.2; and @clerk/shared 2.22.1, 3.47.4, anc 4.8.1
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Interpretation Conflict
Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in astro
- 8.1 High severity
Recent Interpretation Conflict vulnerabilities
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
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