fluent-plugin-opentelemetry: Denial of Service (DoS) via Large Payloads and Decompression Bombs in `in_opentelemetry`

published 2026-06-26 4 mo ago modified 2026-09-30 39 d ago also GHSA-2jc5-xhx8-qj6h , EUVD-2026-78679

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 links 1

rubygems fluent-plugin-opentelemetry 0.5.3

github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry@ce6c1f2 commit

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 53 d ago (2026-09-16)

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem	package	affected	fixed in
rubygems	fluent-plugin-opentelemetry	<0.5.3	0.5.3

Affected products

fluent-plugins-nursery fluent-plugin-opentelemetry

Classification

Weakness

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

References

Sources

Fencer Vulns 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.

Summary