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Fencer Intel
low 2.7

CVE-2026-44162 json

fluent-plugin-s3: Denial of Service (DoS) via Decompression Bomb in `in_s3`

published 4mo ago modified last mo. also GHSA-xv9w-7v6q-hpjh , EUVD-2026-77705

cvss
2.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

fluent-plugin-s3 is an Amazon S3 input and output plugin for Fluentd. From 0.7.0 to 1.8.4, the in_s3 input plugin reads the entire decompressed payload of gzip, lzma2, and lzop objects into memory without enforcing a decompression_size_limit. An attacker with permission to upload objects to the monitored S3 bucket can provide a highly compressed object that expands excessively when Fluentd processes it. The resulting memory exhaustion can cause the operating system to terminate the Fluentd process and disrupt all log collection on the affected node. This issue is fixed in version 1.8.5.

Patch / fix

  • rubygems fluent-plugin-s3 1.8.5

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 2.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 2.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
rubygems fluent-plugin-s3
>=0.7.0, <1.8.5
1.8.5

Affected products

  • fluent fluent-plugin-s3

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.