NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or timeout. An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU saturation that blocks the Python process.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep
    module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/
    pattern nodes and executes them via re.search against tree node labels without any validation or timeout.
    An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to
    external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU
    saturation that blocks the Python process. (CVE-2026-80206)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep     module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/     pattern nodes and executes them via re.search against tree node labels without any validation or timeout.
    An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to     external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU     saturation that blocks the Python process. (CVE-2026-80206)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
464850	Echo: nltk: security update to 3.10.3	Tenable Cloud Security	Echo Local Security Checks	Local	high
464850	Echo: nltk: security update to 3.10.3	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
340828	Linux Distros Unpatched Vulnerability : CVE-2026-80206	Nessus	Misc.	Local	high

Detections

Analytics

CVE-2026-80206

high

Tenable Plugins

high

high

high