CVE-2026-121564

1.8 LOW 0.3% exploit odds Fix listed Other Library

What it is

Incomplete Comparison with Missing Factors (CWE-1023) in merge_chats() (whatstk/utils/chat_merge.py), reached from BaseChat.merge(), in whatstk from 0.3.0 before 0.9.0 allows a party that supplies the chat exports to cause messages to be absent from the merged output with no indication that anything was removed, because the merge keeps whole the chat whose first message is oldest and appends from the other only the messages that are strictly newer than the last message of the first. Every message of the second chat that falls inside the date range already covered by the first is therefore discarded. The two chats are compared on their date ranges and not on the identity of the individual messages, so a message held by only one of the two exports is dropped whenever its date falls inside the range of the other, and both branches of _merge_two_chats() behave this way. The merged result is returned without a warning and without a count of what was removed. This results in a merged chat that omits messages the inputs contain, in a library whose documented uses include forensic review and the generation of training data.

At a glance

Exploitability: Can be exploited locally on the machine without logging in, but needs a user to act. Limited direct impact.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-11-03 16:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-03 18:17 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 1.8 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-11-03 16:17 UTC
Last modified: 2026-11-03 18:17 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-1023
Record status: Deferred

Attack profile CVSS 4.0 · 1.8

Attack vector: Local
Complexity: Low
Attack requirements: Present
Privileges needed: None
User interaction: Active
Confidentiality: None
Integrity: Low
Availability: None

Raw vector

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-121564.md and follow it. Check whether this project is affected by CVE-2026-121564. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record