{"schema":"threatline.record/2","record":{"id":"CVE-2026-12372","aliases":["GHSA-2jhm-w3mp-jcwr","PYSEC-2026-3955"],"summary":"NLTK network URL validation permits SSRF to RFC 6598 shared-address-space hosts","details":"A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the current develop branch. The `nltk.pathsec.validate_network_url()` function, intended to prevent SSRF by rejecting internal network addresses, fails to reject IPs in the RFC 6598 shared address space (`100.64.0.0/10`). This occurs because Python's `ipaddress` module does not classify such addresses as `is_private` or `is_global`, and the current guard only checks `is_private` and a few explicit categories. An attacker who can influence a URL passed to NLTK's network-loading helpers can exploit this vulnerability to make a strict-mode application send requests to shared-address-space hosts, potentially exposing non-public infrastructure reachable from the application host. The impact is limited to SSRF-style confidentiality exposure, with no code execution claimed.","categories":["Libraries & packages"],"product":"nltk","vendor":"nltk","ecosystem":"pip","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-2jhm-w3mp-jcwr","source_modified_at":"2026-10-02T23:11:24Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"nltk"},"range":"< 3.10.0"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-12372","source_modified_at":"2026-08-12T17:48:54.679Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"nltk/nltk","vendor":"nltk","versions":[{"version":"unspecified","status":"affected","versionType":"custom","lessThanOrEqual":"latest"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-2jhm-w3mp-jcwr","source_modified_at":"2026-10-02T23:40:41.750758387Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"nltk","ecosystem":"PyPI","purl":"pkg:pypi/nltk"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.0"}]}],"versions":["0.8","0.9","0.9.3","0.9.4","0.9.5","0.9.6","0.9.7","0.9.8","0.9.9","2.0.1","2.0.1rc1","2.0.1rc2-git","2.0.1rc3","2.0.1rc4","2.0.2","2.0.3","2.0.4","2.0.5","2.0b4","2.0b5","2.0b6","2.0b7","2.0b8","2.0b9","3.0.0","3.0.0b1","3.0.0b2","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.1","3.2","3.2.1","3.2.2","3.2.3","3.2.4","3.2.5","3.3","3.4","3.4.1","3.4.2","3.4.3","3.4.4","3.4.5","3.5","3.5b1","3.6","3.6.1"]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-2jhm-w3mp-jcwr","source_modified_at":"2026-10-02T23:11:24Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"pip","name":"nltk"},"version":"3.10.0"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-2jhm-w3mp-jcwr","source_modified_at":"2026-10-02T23:40:41.750758387Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"nltk","ecosystem":"PyPI","purl":"pkg:pypi/nltk"},"version":"3.10.0"}],"cvss":3.7,"severity":"Low","kev":{"listed":false},"epss":{"probability":0.0026,"percentile":0.16737,"score_date":"2026-10-23"},"published_at":"2026-08-09T22:45:52.799Z","modified_at":"2026-10-02T23:40:41.750758387Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-2jhm-w3mp-jcwr","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-02T23:11:24Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-12372","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-08-12T17:48:54.679Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-2jhm-w3mp-jcwr","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-02T23:40:41.750758387Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-12372","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-12372","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491db","tags":["exploit"]},{"url":"https://github.com/nltk/nltk/commit/4a820afa58810cd05049b6c6eae306694d6cfe65","source":"GitHub Advisory Database"},{"url":"https://github.com/nltk/nltk/releases/tag/v3.10.0","source":"GitHub Advisory Database"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3955.yaml","source":"GitHub Advisory Database"},{"url":"https://github.com/advisories/GHSA-2jhm-w3mp-jcwr","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"poc","automatable":"no","technical_impact":"partial","assessed_at":"2026-08-12T17:45:59.173613Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-02T23:40:41.750758387Z","content_hash":"6971ef135ada0cdeb851ccdb32db92be9425887776f86a17cd8c76aff2c18673"}}