Improper handling of highly compressed data in Fluentd - #VU152736
Published: September 29, 2026
Vulnerability identifier: #VU152736
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-409
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of highly compressed data in the `in_http` plugin's ndjson parsing logic when processing highly compressed ndjson HTTP payloads. A remote attacker can send a crafted payload containing millions of extremely short lines to exhaust memory and cause a denial of service.
The decompressed payload can pass the configured decompression size limit while allocation of individual string objects exhausts system memory.
Affected software
Fluentd
Remediation
Install security update from vendor's website.
Fluentd - update to 1.19.4