SSRF (Server-Side Request Forgery) in nltk (CVE-2026-12372)
Summary
SSRF in nltk (CVE-2026-12372). Risk of unauthorized operations or information disclosure. Exploitable via ipaddress. Mitigation: upgrade to 3.10.0 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-12372 has been found in nltk.
Attackers can target a specific entry point like ipaddress over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade nltk to 3.10.0 or later.
If unsure, ask your IT team or search "nltk CVE-2026-12372" on the vendor's site.
CVE-2026-12372 (nltk) — CWE-918 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: ipaddress / is_private / is_global
Patched: 3.10.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
SSRF (CWE-918) exists in nltk. Attackers reach the vulnerable code path via ipaddress without authentication.
Check the vendor advisory for the affected versions of nltk. Attack surface: ipaddress / is_private / is_global.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to 3.10.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'nltk' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'nltk' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
nltkを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade nltk to 3.10.0ステージング環境で 3.10.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-12372 nltk
- Ubuntu UBUNTU-CVE-2026-12372 nltk
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- report huntr.com
- web github.com
- web github.com
- web github.com