Fluentd is Vulnerable to Denial of Service (DoS) via Gzip Decompression Bomb in `in_http` and `in_forward`
Affects fluentdSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 1.19.3 soon.
Data as of 27 Oct 2026, 05:11 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.19.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade fluentd to 1.19.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| RubyGemsfluentd | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in Fluentd version 1.19.3. Users should upgrade to version 1.19.3 or later to remediate this vulnerability. No other mitigations are indicated by the vendor advisory.
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.
References
- github.com/fluent/fluentd/commit/f5f2b7cddf8aab3932e6dec9fa367a5f3eb27e10 (opens in a new tab)
- github.com/fluent/fluentd/pull/5393 (opens in a new tab)
- github.com/fluent/fluentd/releases/tag/v1.19.3 (opens in a new tab)
- github.com/fluent/fluentd/security/advisories/GHSA-j9cw-hwqf-85w7 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-44160 (opens in a new tab)