VulnerabilityPublished 13 Aug 2026Updated 17 Sep 2026

CVE-2026-33230: Gptline · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in nltk

Affects gptlineSource GCVE Database

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Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.0.8_16 when convenient.

Data as of 1 Nov 2026, 11:02 UTC

CVSS 3.1 base score

6.1Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.0.8_16

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade gptline to 1.0.8_16.

Affected software

Product	Affected	Fixed in
Homebrewgptline`pkg:brew/gptline`Other threats	Affected >=1.0.8 <1.0.8_16	Fixed in 1.0.8_16

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available for this vulnerability. Users should update to a fixed version of the nltk package that properly escapes user input in the lookup_ route. Until patched, users should avoid opening untrusted lookup_ URLs in the WordNet Browser application.

Description

NLTK's WordNet Browser web UI contains a reflected cross-site scripting (XSS) vulnerability in the lookup route. The issue arises because attacker-controlled input is reflected into the HTML response without proper escaping, allowing injection of arbitrary JavaScript. This affects users running the local or self-hosted WordNet Browser HTTP service. Exploitation requires convincing a user to open a crafted URL, leading to script execution within the browser context of the application.

Impact

An attacker who can trick a user into opening a maliciously crafted lookup_ URL can execute arbitrary JavaScript in the browser context of the local WordNet Browser application. This can lead to manipulation of page content, execution of same-origin requests within the app, and potentially triggering UI actions. The impact is limited to users running the local or self-hosted WordNet Browser service and opening attacker-controlled links.

Summary

The vulnerability exists in the nltk.app.wordnet_app module, specifically in the lookup_ route where the 'word' parameter is derived from attacker-controlled base64-encoded pickle data decoded by Reference.decode(). This 'word' is reflected directly into the HTML response without escaping, unlike the search route which properly escapes input. Because the server listens on all interfaces by default, an attacker can craft a URL that injects arbitrary HTML/JavaScript into the response page, resulting in reflected XSS. The issue was demonstrated with a proof-of-concept payload that injects a script alert.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Sep 2026, 01:51 UTC

Technical details

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