lucasrodes whatstk up to 0.8.x Zip Loader parser.py _str_from_file data amplification

Summaryinfo

A vulnerability, which was classified as problematic, was found in lucasrodes whatstk up to 0.8.x. Affected by this issue is the function _str_from_file of the file whatstk/whatsapp/parser.py of the component Zip Loader. Executing a manipulation can lead to data amplification. This vulnerability appears as CVE-2026-121691. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in lucasrodes whatstk up to 0.8.x. This vulnerability affects the function _str_from_file of the file whatstk/whatsapp/parser.py of the component Zip Loader. The manipulation with an unknown input leads to a data amplification vulnerability. The CWE definition for the vulnerability is CWE-409. The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. As an impact it is known to affect availability. CVE summarizes:

Improper Handling of Highly Compressed Data (CWE-409) in the ZIP loader of whatstk from 0.7.0 before 0.9.0 allows a party that supplies a chat export to exhaust the memory and the disk of the process that parses it, because _str_from_file() (whatstk/whatsapp/parser.py) calls zip_ref.extractall() with no bound on the size of the members and no check of the compression ratio, then reads the extracted file in full with f.read(). The only guard on the archive counts the extracted files and raises when there is not exactly one, but it runs after extractall() has already written them, so it does not prevent the cost. _clean_text() then passes the whole text through unicodedata.normalize("NFKD", text), which holds a second copy, and the parse builds a list of regular expression matches and a DataFrame over it, so peak memory is a multiple of the decompressed text rather than of the archive. A ZIP is a documented input of WhatsAppChat.from_source() and df_from_whatsapp(), and is the form in which WhatsApp exports a chat on iOS, so the attacker supplies the whole file. This results in a small upload costing hundreds of megabytes of memory and of disk, and in the process being killed where that exceeds what is available.

The advisory is available at github.com. This vulnerability was named CVE-2026-121691 since 11/03/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 0.9.0 eliminates this vulnerability.

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Productinfo

Vendor

• lucasrodes

Name

• whatstk

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8

Website

• Product: https://github.com/lucasrodes/whatstk/

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