What’s Vulnerable › Vulnerabilities

CVE-2026-44160: Fluentd: Denial of Service (DoS) via Gzip Decompression Bomb in `in_http` and `in_forward`

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-409

Description

Fluentd collects events from various data sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop and so on. Prior to 1.19.3, Fluentd's in_http and in_forward plugins support gzip-compressed data but enforce limits only on compressed payloads through settings such as body_size_limit and chunk_size_limit, allowing crafted compressed payloads to decompress in memory to an excessive size and cause denial of service through memory exhaustion. This issue is fixed in version 1.19.3.

Affected products

• fluentd: before 1.19.3 — fixed in 1.19.3

How to fix

Upgrade to a fixed version: fluentd 1.19.3. Check the vendor advisory for mitigations.

References

• https://github.com/fluent/fluentd/commit/f5f2b7cddf8aab3932e6dec9fa367a5f3eb27e10
• https://github.com/fluent/fluentd/pull/5393
• https://github.com/fluent/fluentd/releases/tag/v1.19.3
• https://github.com/fluent/fluentd/security/advisories/GHSA-j9cw-hwqf-85w7

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