CVE-2021-42391

unknown

Published — · Modified —

CVSS v3

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CVSS v2

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VIR risk

—

Description

Divide-by-zero in Clickhouse's Gorilla compression codec when parsing a malicious query. The first byte of the compressed buffer is used in a modulo operation without being checked for 0.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-42391

OS impact

OS	Version	Status	Fixed in
debian	bookworm	fixed	`0`
debian	bullseye	fixed	`0`

References

https://security-tracker.debian.org/tracker/CVE-2021-42391

Verify integrity in audit chain (admin only). AS-IS.