Fluentd: Server-Side Request Forgery (SSRF) via Placeholder Expansion in `out_http`

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Summary

CVECVE-2026-44161
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-08 22:17:14 UTC
Updated2026-07-10 17:49:57 UTC
DescriptionFluentd collects events from various data sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop and so on. Prior to 1.19.3, the Fluentd out_http output plugin allows placeholders such as ${tag} in the endpoint configuration parameter, and if a placeholder value is derived from untrusted input an attacker can control the destination hostname of outbound HTTP requests and force requests to arbitrary internal services. This issue is fixed in version 1.19.3.

Risk And Classification

Primary CVSS: v3.1 7.2 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L

EPSS: 0.004490000 probability, percentile 0.361260000 (date 2026-07-11)

Problem Types: CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L
3.1CNADECLARED7.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Fluent Fluentd affected < 1.19.3 Not specified

References

ReferenceSourceLinkTags
github.com/fluent/fluentd/commit/c6a01ea2e0ea01977f8d615f7c6dbfae4cba88c9 [email protected] github.com
github.com/fluent/fluentd/releases/tag/v1.19.3 [email protected] github.com
github.com/fluent/fluentd/security/advisories/GHSA-72f5-rr8c-r6gr [email protected] github.com
github.com/fluent/fluentd/pull/5394 [email protected] github.com
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