{"vulnerability": "cve-2026-61629", "sightings": [{"uuid": "db590a1e-a039-4da2-9910-b7178a835da5", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "86ecb4e1-bb32-44d5-9f39-8a4673af8385", "vulnerability": "CVE-2026-61629", "type": "published-proof-of-concept", "source": "https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx", "content": "", "creation_timestamp": "2026-09-21T22:35:04.448718Z"}, {"uuid": "d76d88a5-3cdb-414f-a4a8-0c8b70dcd3cd", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-61629", "type": "seen", "source": "https://gist.github.com/alon710/ad227f40c773c675cce4604553df73dc", "content": "# CVE-2026-61629: CVE-2026-61629: CPU Amplification Denial of Service via ParseAcceptLanguage Underscore Bypass\n\n> **CVSS Score:** 7.5\n> **Published:** 2026-09-21\n> **Full Report:** https://cvereports.com/reports/CVE-2026-61629\n\n## Summary\nA vulnerability exists in the i18n middleware of nginx-ignition, enabling CPU amplification attacks. By transmitting a crafted Accept-Language header containing malformed tags separated by underscores, an unauthenticated remote attacker can bypass the length-guard threshold of the underlying Go parsing library. Normalization of underscores to hyphens occurs after the initial validation checks, forcing the parser into expensive quadratic-time loops that consume 100% of available CPU resources. This leads to a complete denial of service for the administrative API and potentially degrades the availability of the hosting system. This vulnerability has been resolved in version 2.40.1.\n\n## TL;DR\nUnauthenticated remote CPU amplification vulnerability in nginx-ignition version 2.29.0 through 2.40.0 allowed attackers to trigger a Denial of Service (DoS) by sending crafted Accept-Language headers with excessive underscore separators.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-770\n- **Attack Vector**: Network\n- **CVSS Score**: 7.5\n- **EPSS Score**: 0.0\n- **Exploit Status**: PoC\n- **KEV Status**: Not Listed\n\n## Affected Systems\n\n- nginx-ignition versions 2.29.0 through 2.40.0\n\n## Mitigation\n\n- Upgrade nginx-ignition to version 2.40.1 or above.\n- Deploy reverse-proxy or WAF rules to sanitize or drop excessively long Accept-Language headers with underscores or hyphens.\n- Restrict access to administrative ports using network firewalls or access control lists.\n\n**Remediation Steps:**\n1. Identify running instances of nginx-ignition and verify their active version.\n2. Apply the updated release 2.40.1 or rebuild with Go 1.25.6 and upgraded text dependencies.\n3. Configure Nginx upstream reverse proxy filtering for Accept-Language headers if deployment patches are delayed.\n4. Restart the service and monitor CPU metrics under load.\n\n## References\n\n- [GitHub Security Advisory GHSA-jr34-h97m-9hpx](https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx)\n- [Commit 0c988fc1277c7d291725e8373313f8486fa1b31a](https://github.com/lucasdillmann/nginx-ignition/commit/0c988fc1277c7d291725e8373313f8486fa1b31a)\n- [Commit cbaf0fc16ed873f7178a2ca9b0d00a696e44b485](https://github.com/lucasdillmann/nginx-ignition/commit/cbaf0fc16ed873f7178a2ca9b0d00a696e44b485)\n- [Release v2.40.1](https://github.com/lucasdillmann/nginx-ignition/releases/tag/2.40.1)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-61629) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-09-21T23:31:26.912461Z"}, {"uuid": "2f420585-5e28-4096-8799-302a8b3b82ee", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-61629", "type": "seen", "source": "https://gist.github.com/alon710/ad227f40c773c675cce4604553df73dc", "content": "# CVE-2026-61629: CVE-2026-61629: CPU Amplification Denial of Service via ParseAcceptLanguage Underscore Bypass\n\n> **CVSS Score:** 7.5\n> **Published:** 2026-09-21\n> **Full Report:** https://cvereports.com/reports/CVE-2026-61629\n\n## Summary\nA vulnerability exists in the i18n middleware of nginx-ignition, enabling CPU amplification attacks. By transmitting a crafted Accept-Language header containing malformed tags separated by underscores, an unauthenticated remote attacker can bypass the length-guard threshold of the underlying Go parsing library. Normalization of underscores to hyphens occurs after the initial validation checks, forcing the parser into expensive quadratic-time loops that consume 100% of available CPU resources. This leads to a complete denial of service for the administrative API and potentially degrades the availability of the hosting system. This vulnerability has been resolved in version 2.40.1.\n\n## TL;DR\nUnauthenticated remote CPU amplification vulnerability in nginx-ignition version 2.29.0 through 2.40.0 allowed attackers to trigger a Denial of Service (DoS) by sending crafted Accept-Language headers with excessive underscore separators.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-770\n- **Attack Vector**: Network\n- **CVSS Score**: 7.5\n- **EPSS Score**: 0.0\n- **Exploit Status**: PoC\n- **KEV Status**: Not Listed\n\n## Affected Systems\n\n- nginx-ignition versions 2.29.0 through 2.40.0\n\n## Mitigation\n\n- Upgrade nginx-ignition to version 2.40.1 or above.\n- Deploy reverse-proxy or WAF rules to sanitize or drop excessively long Accept-Language headers with underscores or hyphens.\n- Restrict access to administrative ports using network firewalls or access control lists.\n\n**Remediation Steps:**\n1. Identify running instances of nginx-ignition and verify their active version.\n2. Apply the updated release 2.40.1 or rebuild with Go 1.25.6 and upgraded text dependencies.\n3. Configure Nginx upstream reverse proxy filtering for Accept-Language headers if deployment patches are delayed.\n4. Restart the service and monitor CPU metrics under load.\n\n## References\n\n- [GitHub Security Advisory GHSA-jr34-h97m-9hpx](https://github.com/lucasdillmann/nginx-ignition/security/advisories/GHSA-jr34-h97m-9hpx)\n- [Commit 0c988fc1277c7d291725e8373313f8486fa1b31a](https://github.com/lucasdillmann/nginx-ignition/commit/0c988fc1277c7d291725e8373313f8486fa1b31a)\n- [Commit cbaf0fc16ed873f7178a2ca9b0d00a696e44b485](https://github.com/lucasdillmann/nginx-ignition/commit/cbaf0fc16ed873f7178a2ca9b0d00a696e44b485)\n- [Release v2.40.1](https://github.com/lucasdillmann/nginx-ignition/releases/tag/2.40.1)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-61629) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-09-22T00:01:48.548139Z"}]}