Answer in brief
CVE-2026-12372 records a Low severity (CVSS 3.7) vulnerability in Server-Side Request Forgery (SSRF) in nltk/nltk. The current sources do not mark it as known exploited. The current feed maps nltk/nltk/nltk (generic), nltk (pip), nltk (pypi), nltk (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 3.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps nltk/nltk/nltk (generic), nltk (pip), nltk (pypi), nltk (pypi). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| nltk/nltk/nltkgeneric | unspecified | Not reported |
| nltkpip | <3.10.0 | 3.10.0 |
| nltkpypi | >=0 <3.10.0 | 3.10.0 |
| nltkpypi | >=0 | Not reported |
Published upstream
Aug 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 9, 2026
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.
Quoted source text, attributed separately from HOL analysis.