VulnerabilityPublished 13 Aug 2026Updated 5 Nov 2026

CVE-2026-33236: Gptline · NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite

Affects gptlineSource GCVE Database

Compare

Not known to be exploited · CVSS 8.1 High : upgrade to 1.0.8_16 soon.

Data as of 5 Nov 2026, 05:58 UTC

CVSS 3.1 base score

8.1High

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

Patch: Available – fixed in 1.0.8_16

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

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

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: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

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 5 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.

Patches and advisories

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 in NLTK version 1.0.8_16 that addresses this vulnerability. Users should upgrade to version 1.0.8_16 or later to remediate the issue. Until patched, avoid using untrusted or attacker-controlled XML index servers with the NLTK downloader. No vendor advisory indicates that no action is required or that the issue is already mitigated without patching.

Description

NLTK's downloader component contains a path traversal vulnerability in its handling of remote XML index files. The vulnerability arises because the downloader does not validate the 'subdir' and 'id' attributes, allowing an attacker controlling a remote XML index server to specify path traversal sequences. This can lead to arbitrary directory creation and arbitrary file overwrite on the victim's file system, including critical system files such as /etc/passwd. The vulnerability is identified as CVE-2026-33236 and has a high severity with a CVSS score of 8.1. A fix is available in version 1.0.8_16.

Impact

Successful exploitation allows an attacker to create directories and overwrite arbitrary files on the victim's file system, including critical system files. This can lead to system compromise, denial of service, or unauthorized access. The integrity and availability of the affected system are severely impacted. Confidentiality is not directly affected according to the CVSS vector.

Summary

The NLTK downloader processes remote XML index files without validating the 'subdir' and 'id' attributes. These attributes are used directly to construct file paths, enabling path traversal attacks. An attacker controlling the remote XML index server can craft malicious XML entries with path traversal sequences (e.g., '../../') that cause the downloader to create directories and write files outside the intended download directory. This can result in overwriting critical system files such as /etc/passwd or ~/.ssh/authorized_keys. The vulnerability is demonstrated with proof-of-concept code showing a malicious server serving crafted XML and a zip file, and an exploit script that triggers the downloader to write files to arbitrary locations. The vulnerability affects versions >=1.0.8 and <1.0.8_16, with version 1.0.8_16 containing the fix. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H, indicating network attack vector, low complexity, no privileges required, user interaction required, unchanged scope, no confidentiality impact, high integrity impact, and high availability impact.

References

Community reviews

Loading reviews…