{"vulnerability": "cve-2026-66062", "sightings": [{"uuid": "d26021ca-8c0d-45dc-97b3-43a15b4959ce", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-66062", "type": "seen", "source": "https://gist.github.com/alon710/47ff7eb96677e04e1cb388be69ae9049", "content": "# CVE-2026-66062: CVE-2026-66062: Regular Expression Denial of Service (ReDoS) in SvelteKit Content Negotiation\n\n> **CVSS Score:** 5.3\n> **Published:** 2026-08-07\n> **Full Report:** https://cvereports.com/reports/CVE-2026-66062\n\n## Summary\nA Regular Expression Denial of Service (ReDoS) vulnerability exists in SvelteKit's content negotiation header parser prior to version 2.70.2. An unauthenticated remote attacker can exploit this vulnerability by sending a crafted Accept header with highly repetitive malformed values. This triggers catastrophic backtracking on the single-threaded Node.js/Bun event loop, leading to CPU exhaustion and full denial of service.\n\n## TL;DR\nSvelteKit versions before 2.70.2 are vulnerable to a CPU-exhausting ReDoS via malformed Accept headers due to an unanchored regular expression in its content negotiation parser.\n\n## Technical Details\n\n- **CWE ID**: CWE-1333 (Inefficient Regular Expression Complexity)\n- **Attack Vector**: Network (AV:N)\n- **CVSS**: 5.3 (Medium)\n- **EPSS**: N/A\n- **Impact**: Denial of Service (DoS)\n- **Exploit Status**: PoC Available\n- **KEV Status**: Not Listed\n\n## Affected Systems\n\n- SvelteKit Server Applications\n- Node.js execution environments running @sveltejs/kit\n- Bun execution environments running @sveltejs/kit\n- **@sveltejs/kit**: < 2.70.2 (Fixed in: `2.70.2`)\n\n## Mitigation\n\n- Upgrade to @sveltejs/kit version 2.70.2 or later\n- Enforce strict HTTP header size limit in reverse proxies\n- Deploy WAF rules to reject Accept headers without forward slashes\n\n**Remediation Steps:**\n1. Open your project's package.json file\n2. Update the @sveltejs/kit dependency to ^2.70.2\n3. Run your package manager's installation command (e.g., npm install or pnpm install) to update lockfiles\n4. Deploy the updated code to production environments\n\n## References\n\n- [GitHub Security Advisory GHSA-29g2-3rmr-qm68](https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68)\n- [SvelteKit Fix Commit 82712fc02c24b1dcf5b25d7a52129cd8455f04f5](https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5)\n- [NVD Entry for CVE-2026-66062](https://nvd.nist.gov/vuln/detail/CVE-2026-66062)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-66062) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-08-08T08:31:57.841681Z"}]}