https://vulnerability.circl.lu Contains only the most 10 recent sightings. http://www.rssboard.org/rss-specification python-feedgen en Fri, 11 Sep 2026 19:04:04 +0000 https://vulnerability.circl.lu/sighting/b01c4778-5c86-4ddc-906c-91a24d34f756/export {"uuid": "b01c4778-5c86-4ddc-906c-91a24d34f756", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-63311", "type": "seen", "source": "https://gist.github.com/alon710/d2b8511d121d9c8c1d87b14251d4a3da", "content": "# CVE-2026-63311: CVE-2026-63311: Server-Side Request Forgery and DNS Rebinding in Natural Language Toolkit (NLTK)\n\n> **CVSS Score:** 6.9\n> **Published:** 2026-09-02\n> **Full Report:** https://cvereports.com/reports/CVE-2026-63311\n\n## Summary\nA vulnerability in the Natural Language Toolkit (NLTK) before version 3.10.0 allowed attackers to bypass SSRF filters via DNS resolution failures and DNS rebinding. By exploiting these weaknesses, unauthenticated remote attackers could coerce hosting systems into scanning internal networks or accessing sensitive cloud metadata endpoints.\n\n## TL;DR\nNLTK versions prior to 3.10.0 are vulnerable to Server-Side Request Forgery (SSRF) and DNS rebinding. Due to fail-open exception handling in DNS resolution and a lack of IP pinning, security checks on remote URLs can be completely bypassed by attackers controlling the target server or domain.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-918\n- **Attack Vector**: Network\n- **CVSS v4.0 Score**: 6.9\n- **EPSS Score**: 0.00241\n- **Exploit Status**: Proof of Concept\n- **CISA KEV Status**: No\n\n## Affected Systems\n\n- Python environments utilizing the nltk library\n- **nltk**: < 3.10.0 (Fixed in: `3.10.0`)\n\n## Mitigation\n\n- Upgrade the NLTK library to version 3.10.0 or higher immediately.\n- Implement outbound firewall rules to prevent application servers from reaching private IP addresses.\n- Configure local DNS servers with anti-DNS-rebinding protection to drop responses mapping to loopback or RFC 1918 ranges.\n- Disable or restrict dynamic network-based resource loading within NLTK unless strictly required.\n\n**Remediation Steps:**\n1. Identify all systems running Python workloads with the NLTK package installed.\n2. Execute 'pip install --upgrade nltk>=3.10.0' to update the library to the patched release.\n3. Verify the installed version using 'python -c \"import nltk; print(nltk.__version__)\"'.\n4. Apply outbound firewall blocks on target servers to restrict egress to the local metadata IP '169.254.169.254'.\n\n## References\n\n- [GitHub Security Advisory GHSA-3gqm-fcw5-w839](https://github.com/nltk/nltk/security/advisories/GHSA-3gqm-fcw5-w839)\n- [NVD Vulnerability Page for CVE-2026-63311](https://nvd.nist.gov/vuln/detail/CVE-2026-63311)\n- [VulnCheck Security Advisory](https://www.vulncheck.com/advisories/nltk-before-ssrf-via-dns-resolution-failure)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-63311) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-09-02T21:32:05.530622Z"} {"uuid": "b01c4778-5c86-4ddc-906c-91a24d34f756", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-63311", "type": "seen", "source": "https://gist.github.com/alon710/d2b8511d121d9c8c1d87b14251d4a3da", "content": "# CVE-2026-63311: CVE-2026-63311: Server-Side Request Forgery and DNS Rebinding in Natural Language Toolkit (NLTK)\n\n> **CVSS Score:** 6.9\n> **Published:** 2026-09-02\n> **Full Report:** https://cvereports.com/reports/CVE-2026-63311\n\n## Summary\nA vulnerability in the Natural Language Toolkit (NLTK) before version 3.10.0 allowed attackers to bypass SSRF filters via DNS resolution failures and DNS rebinding. By exploiting these weaknesses, unauthenticated remote attackers could coerce hosting systems into scanning internal networks or accessing sensitive cloud metadata endpoints.\n\n## TL;DR\nNLTK versions prior to 3.10.0 are vulnerable to Server-Side Request Forgery (SSRF) and DNS rebinding. Due to fail-open exception handling in DNS resolution and a lack of IP pinning, security checks on remote URLs can be completely bypassed by attackers controlling the target server or domain.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-918\n- **Attack Vector**: Network\n- **CVSS v4.0 Score**: 6.9\n- **EPSS Score**: 0.00241\n- **Exploit Status**: Proof of Concept\n- **CISA KEV Status**: No\n\n## Affected Systems\n\n- Python environments utilizing the nltk library\n- **nltk**: < 3.10.0 (Fixed in: `3.10.0`)\n\n## Mitigation\n\n- Upgrade the NLTK library to version 3.10.0 or higher immediately.\n- Implement outbound firewall rules to prevent application servers from reaching private IP addresses.\n- Configure local DNS servers with anti-DNS-rebinding protection to drop responses mapping to loopback or RFC 1918 ranges.\n- Disable or restrict dynamic network-based resource loading within NLTK unless strictly required.\n\n**Remediation Steps:**\n1. Identify all systems running Python workloads with the NLTK package installed.\n2. Execute 'pip install --upgrade nltk>=3.10.0' to update the library to the patched release.\n3. Verify the installed version using 'python -c \"import nltk; print(nltk.__version__)\"'.\n4. Apply outbound firewall blocks on target servers to restrict egress to the local metadata IP '169.254.169.254'.\n\n## References\n\n- [GitHub Security Advisory GHSA-3gqm-fcw5-w839](https://github.com/nltk/nltk/security/advisories/GHSA-3gqm-fcw5-w839)\n- [NVD Vulnerability Page for CVE-2026-63311](https://nvd.nist.gov/vuln/detail/CVE-2026-63311)\n- [VulnCheck Security Advisory](https://www.vulncheck.com/advisories/nltk-before-ssrf-via-dns-resolution-failure)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-63311) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-09-02T21:32:05.530622Z"} https://vulnerability.circl.lu/sighting/b01c4778-5c86-4ddc-906c-91a24d34f756/export Wed, 02 Sep 2026 21:32:05 +0000 https://vulnerability.circl.lu/sighting/5a1772d3-c1ad-45ab-b977-ee809e1e2130/export {"uuid": "5a1772d3-c1ad-45ab-b977-ee809e1e2130", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "86ecb4e1-bb32-44d5-9f39-8a4673af8385", "vulnerability": "CVE-2026-63311", "type": "published-proof-of-concept", "source": "https://github.com/nltk/nltk/security/advisories/GHSA-3gqm-fcw5-w839", "content": "", "creation_timestamp": "2026-09-02T16:35:05.215429Z"} {"uuid": "5a1772d3-c1ad-45ab-b977-ee809e1e2130", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "86ecb4e1-bb32-44d5-9f39-8a4673af8385", "vulnerability": "CVE-2026-63311", "type": "published-proof-of-concept", "source": "https://github.com/nltk/nltk/security/advisories/GHSA-3gqm-fcw5-w839", "content": "", "creation_timestamp": "2026-09-02T16:35:05.215429Z"} https://vulnerability.circl.lu/sighting/5a1772d3-c1ad-45ab-b977-ee809e1e2130/export Wed, 02 Sep 2026 16:35:05 +0000