High [CVE-2026-71513] Remote Code Execution via AllowlistUnpickler dotted-name bypass
This high-severity Red Hat Linux advisory covers CVE-2026-71513 affecting Lightspeed Core, OpenShift Lightspeed.
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Summary
NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace.
Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load. A flaw was found in NLTK.
A remote attacker can achieve remote code execution by crafting untrusted transition-parser models. This allows attackers to bypass the allowlist by resolving dotted names through attribute traversal, leading to the execution of arbitrary commands when `TransitionParser.parse` loads a malicious model.
This can lead to arbitrary command execution and full system compromise in affected Red Hat products, including OpenShift Lightspeed and Lightspeed Core, which may process external data using NLTK. Red Hat severity: Important — CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
Weakness: CWE-502. Red Hat lists Exploit Intelligence; OpenShift Lightspeed; Red Hat Ansible Automation Platform 2; Red Hat OpenShift AI (RHOAI) as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
- < 3.10.3
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- To mitigate this issue, avoid loading NLTK transition-parser models from untrusted or unverified sources. Ensure that applications processing such models implement robust input validation and only load models from known, secure origins.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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