{"id":"CVE-2026-12372","state":"PUBLISHED","title":"Server-Side Request Forgery (SSRF) in nltk/nltk","description":"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.","publishedAt":"2026-08-09T22:45:52.799Z","updatedAt":"2026-08-12T17:48:54.679Z","severity":{"score":3.7,"label":"Low","version":"3.0","vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"@huntr_ai"},"assigner":"@huntr_ai","products":["nltk nltk/nltk"],"affected":[{"vendor":"nltk","product":"nltk/nltk","versions":[{"version":"unspecified","status":"affected","lessThanOrEqual":"latest","versionType":"custom"}]}],"references":["https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491db"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:10:52.580Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/12xxx/CVE-2026-12372.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-12372","state":"PUBLISHED","datePublished":"2026-08-09T22:45:52.799Z","dateUpdated":"2026-08-12T17:48:54.679Z","assignerShortName":"@huntr_ai","assignerOrgId":"c09c270a-b464-47c1-9133-acb35b22c19a","dateReserved":"2026-06-16T06:05:39.765Z"},"containers":{"cna":{"title":"Server-Side Request Forgery (SSRF) in nltk/nltk","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"nltk","product":"nltk/nltk","versions":[{"version":"unspecified","status":"affected","lessThanOrEqual":"latest","versionType":"custom"}]}],"references":[{"url":"https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491db"}],"metrics":[{"cvssV3_0":{"version":"3.0","attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","baseScore":3.7,"baseSeverity":"LOW"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","type":"CWE","lang":"en","description":"CWE-918 Server-Side Request Forgery (SSRF)"}]}],"providerMetadata":{"shortName":"@huntr_ai","orgId":"c09c270a-b464-47c1-9133-acb35b22c19a","dateUpdated":"2026-08-09T22:45:52.799Z"},"source":{"advisory":"2911b643-571c-42e4-b0c2-9a1fa6f491db","discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://huntr.com/bounties/2911b643-571c-42e4-b0c2-9a1fa6f491db","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-12T17:45:59.173613Z","id":"CVE-2026-12372","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-12T17:48:54.679Z"}}]}}}