NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
💎
💎 RubyGems
Not in CISA KEV
LOW severity

fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via Decompression Bomb in `in_s3`GHSA-xv9w-7v6q-hpjh

LOWFix: fluent/fluent-plugin-s3@e085aee

GHSA-xv9w-7v6q-hpjh is a low-severity (CVSS 2.7) CWE-409 vulnerability in fluent-plugin-s3. A fix is available for fluent-plugin-s3 — see the affected versions and patch details below.

Also known asCVE-2026-44162
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-xv9w-7v6q-hpjh.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk
0.00%0.33%0.66%0.98%0.5%0.5%0.5%Oct 26Nov 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
💎fluent-plugin-s3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

The fluent-plugin-s3 plugin (specifically the in_s3 input plugin) supports reading and decompressing heavily compressed files (such as gzip, lzma2, and lzop) from Amazon S3. It was discovered that the plugin read the entire decompressed payload into memory at once without enforcing a strict size limit.

If an attacker has sufficient permissions to upload files to the monitored S3 bucket, they can upload a maliciously crafted, highly compressed file. When Fluentd attempts to decompress this file, it will expand to an excessive size and it will consume significant system resources.

Impact

This vulnerability allows for a Denial of Service (DoS) attack via memory exhaustion. The rapid memory consumption during decompression can lead to an Out-of-Memory kill of the Fluentd process by the operating system, This results in the disruption of all log collection on the affected node.

Patches

v1.8.5

Workarounds

If an immediate upgrade is not possible, mitigate the risk by applying strict IAM access controls:

  1. Restrict Bucket Access
    • Ensure that write (PUT) access to the S3 bucket monitored by in_s3 is strictly limited to trusted services and administrators. Prevent any public or untrusted uploads to the S3 bucket.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsfluent-plugin-s3≥ 0.7.0&&< 1.8.51.8.5bundle update fluent-plugin-s3 --conservative

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fluent-plugin-s3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update fluent-plugin-s3 to 1.8.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xv9w-7v6q-hpjh is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

The `fluent-plugin-s3` plugin (specifically the `in_s3` input plugin) supports reading and decompressing heavily compressed files (such as `gzip`, `lzma2`, and `lzop`) from Amazon S3. It was discovered that the plugin read the entire decompressed payload into memory at once without enforcing a strict size limit. If an attacker has sufficient permissions to upload files to the monitored S3 bucket, they can upload a maliciously crafted, highly compressed file. When Fluentd attempts to decompress this file, it will expand to an excessive size and it will consume significant system resources. #
O3 Security · Impact-Aware SCA

Is GHSA-xv9w-7v6q-hpjh in your dependencies?

Find it across RubyGems, including transitive dependencies.

Scan my dependencies How O3 SCA works
fluent-plugin-s3 Vulnerable to Denial of Service (DoS) via…