{"items":[{"id":"NVI-00010727","kind":"vulnerability","title":"NLTK: SSRF Fail-Open in validate_network_url() via DNS Resolution Failure","revision":3,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected.","NVD lastModified does not establish freshness of every associated CPE record."],"lifecycle":"active","identifiers":["GHSA-3gqm-fcw5-w839","CVE-2026-63311"],"plain_summary":"GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-0abe557167bddfdb2330916fefcdfce6"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-10-14T13:10:00.187Z","value":"5.3 MEDIUM (3.1)","meaning":"disclosure@vulncheck.com severity; no combined Null risk score.","source_id":"sr-01210cdc577d188fa4612f460a331619"},{"kind":"CVSS","as_of":"2026-10-14T13:10:00.187Z","value":"6.9 MEDIUM (4.0)","meaning":"disclosure@vulncheck.com severity; no combined Null risk score.","source_id":"sr-01210cdc577d188fa4612f460a331619"},{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.334%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.26842. Missing scores are unknown.","source_id":"sr-0abe557167bddfdb2330916fefcdfce6"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-d2b2691573a35a9513e24d162983e653","url":"https://github.com/advisories/GHSA-3gqm-fcw5-w839","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-3gqm-fcw5-w839","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T22:06:46.371Z"},{"id":"sr-01210cdc577d188fa4612f460a331619","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63311","basis":"official_catalog","notes":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","title":"CVE-2026-63311","publisher":"NIST National Vulnerability Database","observed_at":"2026-11-04T02:47:38.696Z"},{"id":"sr-0abe557167bddfdb2330916fefcdfce6","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-63311","publisher":"FIRST EPSS","observed_at":"2026-10-31T23:13:27.698Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-d2b2691573a35a9513e24d162983e653"],"technology":"nltk","known_exclusions":[],"conditions_summary":"There is an SSRF vulnerability in NLTK 3.9.4's network URL validation. The validate_network_url() function in nltk/pathsec.py fails open when DNS resolution returns an error.\n\nThe _resolve_hostname() helper at lines 193-234 catches OSError and ValueError during socket.getaddrinfo() and returns an empty list []. When this happens, the validation loop in validate_network_url() iterates over nothing (for addr in resolved: ... never executes), with no else/fallback check. The function returns normally, and urlopen() proceeds to make the request without any IP validation.\n\nThis means:\n1. If DNS is temporarily unavailable, ALL SSRF protections are disabled\n2. DNS rebinding attacks bypass the check after the LRU cache entry expires\n3. In environments with unreliable resolvers, the protection is permanently bypassed\n\nPoC:\n```python\nimport nltk.pathsec\nimport unittest.mock\n\n# Simulate DNS failure\nwith unittest.mock.patch('socket.getaddrinfo', side_effect=OSError('DNS unavailable')):\n    # This SHOULD raise but doesn't -- fails open\n    nltk.pathsec.validate_network_url('http://169.254.169.254/latest/meta-data/')\n    # Returns normally, allowing SSRF to cloud metadata\n```\n\nThe correct behavi","public_affected_ranges":["<= 3.9.4"]}],"null_published_at":"2026-11-04T10:04:35.893Z","source_updated_at":"2026-10-27T07:58:29.000Z","source_disclosed_at":"2026-09-02T15:39:39.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Source facts changed; compare the preserved prior revision.","null_first_observed_at":"2026-10-31T22:06:46.371Z"},{"id":"NVI-00010727","kind":"vulnerability","title":"NLTK: SSRF Fail-Open in validate_network_url() via DNS Resolution Failure","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-3gqm-fcw5-w839","CVE-2026-63311"],"plain_summary":"GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-0abe557167bddfdb2330916fefcdfce6"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.334%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.26842. Missing scores are unknown.","source_id":"sr-0abe557167bddfdb2330916fefcdfce6"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-d2b2691573a35a9513e24d162983e653","url":"https://github.com/advisories/GHSA-3gqm-fcw5-w839","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-3gqm-fcw5-w839","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T22:06:46.371Z"},{"id":"sr-0abe557167bddfdb2330916fefcdfce6","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-63311","publisher":"FIRST EPSS","observed_at":"2026-10-31T23:13:27.698Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-d2b2691573a35a9513e24d162983e653"],"technology":"nltk","known_exclusions":[],"conditions_summary":"There is an SSRF vulnerability in NLTK 3.9.4's network URL validation. The validate_network_url() function in nltk/pathsec.py fails open when DNS resolution returns an error.\n\nThe _resolve_hostname() helper at lines 193-234 catches OSError and ValueError during socket.getaddrinfo() and returns an empty list []. When this happens, the validation loop in validate_network_url() iterates over nothing (for addr in resolved: ... never executes), with no else/fallback check. The function returns normally, and urlopen() proceeds to make the request without any IP validation.\n\nThis means:\n1. If DNS is temporarily unavailable, ALL SSRF protections are disabled\n2. DNS rebinding attacks bypass the check after the LRU cache entry expires\n3. In environments with unreliable resolvers, the protection is permanently bypassed\n\nPoC:\n```python\nimport nltk.pathsec\nimport unittest.mock\n\n# Simulate DNS failure\nwith unittest.mock.patch('socket.getaddrinfo', side_effect=OSError('DNS unavailable')):\n    # This SHOULD raise but doesn't -- fails open\n    nltk.pathsec.validate_network_url('http://169.254.169.254/latest/meta-data/')\n    # Returns normally, allowing SSRF to cloud metadata\n```\n\nThe correct behavi","public_affected_ranges":["<= 3.9.4"]}],"null_published_at":"2026-10-31T23:18:22.438Z","source_updated_at":"2026-10-27T07:58:29.000Z","source_disclosed_at":"2026-09-02T15:39:39.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.","null_first_observed_at":"2026-10-31T22:06:46.371Z"},{"id":"NVI-00010727","kind":"vulnerability","title":"NLTK: SSRF Fail-Open in validate_network_url() via DNS Resolution Failure","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-3gqm-fcw5-w839","CVE-2026-63311"],"plain_summary":"GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-d2b2691573a35a9513e24d162983e653"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-d2b2691573a35a9513e24d162983e653","url":"https://github.com/advisories/GHSA-3gqm-fcw5-w839","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-3gqm-fcw5-w839","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T22:06:46.371Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-d2b2691573a35a9513e24d162983e653"],"technology":"nltk","known_exclusions":[],"conditions_summary":"There is an SSRF vulnerability in NLTK 3.9.4's network URL validation. The validate_network_url() function in nltk/pathsec.py fails open when DNS resolution returns an error.\n\nThe _resolve_hostname() helper at lines 193-234 catches OSError and ValueError during socket.getaddrinfo() and returns an empty list []. When this happens, the validation loop in validate_network_url() iterates over nothing (for addr in resolved: ... never executes), with no else/fallback check. The function returns normally, and urlopen() proceeds to make the request without any IP validation.\n\nThis means:\n1. If DNS is temporarily unavailable, ALL SSRF protections are disabled\n2. DNS rebinding attacks bypass the check after the LRU cache entry expires\n3. In environments with unreliable resolvers, the protection is permanently bypassed\n\nPoC:\n```python\nimport nltk.pathsec\nimport unittest.mock\n\n# Simulate DNS failure\nwith unittest.mock.patch('socket.getaddrinfo', side_effect=OSError('DNS unavailable')):\n    # This SHOULD raise but doesn't -- fails open\n    nltk.pathsec.validate_network_url('http://169.254.169.254/latest/meta-data/')\n    # Returns normally, allowing SSRF to cloud metadata\n```\n\nThe correct behavi","public_affected_ranges":["<= 3.9.4"]}],"null_published_at":"2026-10-31T22:27:12.378Z","source_updated_at":"2026-10-27T07:58:29.000Z","source_disclosed_at":"2026-09-02T15:39:39.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-10-31T22:06:46.371Z"}],"next_cursor":null,"snapshot_revision":"42594"}