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🛡️ CVE-2026-66062 — kit

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-1333 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header

Impact

SvelteKit is vulnerable to remote CPU-exhaustion DoS attacks via specifically-crafted Accept headers. The impact is mitigated by default header length limits on most platforms, but in the case of raised or absent limits a denial of service is possible.

Patches

The vulnerability is patched in @sveltejs/kit version 2.70.2.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: Low — limited, and the attacker does not choose what is affected.

Weakness class

CVE-2026-66062 is classified as CWE-1333: Inefficient Regular Expression Complexity. A regular expression backtracks catastrophically on crafted input, consuming CPU out of proportion to input size.

Affected software

CVE-2026-66062 is recorded against 2 packages.

  • @sveltejs/kit
  • unknown

Timeline and source

Published on 7 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

Other advisories for this package

@sveltejs/kit has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-1333: Inefficient Regular Expression Complexity) in other software:

Details

Severity Medium
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE CWE-1333
Public Exploit ✅ No
Source NVD
Published 2026-08-07
Updated 2026-08-20
Modified 2026-08-07
Fix URL N/A

Affected Packages

Software From version Fixed in
@sveltejs/kit — —
unknown — —

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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