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GHSA-72f5-rr8c-r6gr

HighCVSS 7.2 / 10
Published Jun 26, 2026·Last modified Jun 26, 2026
Affected Components(0)

No affected components available

Description

The out_http output plugin allows the use of placeholders (such as ${tag}) in the endpoint configuration parameter. It was discovered that if the placeholder value is derived from untrusted user input, an attacker can maliciously control the destination hostname of the outbound HTTP requests made by Fluentd.

Impact

This vulnerability allows for a Server-Side Request Forgery (SSRF) attack. An unauthenticated attacker can force the Fluentd node to send HTTP requests to arbitrary internal services. This can lead to unauthorized access to internal APIs, data exfiltration, or the compromise of cloud metadata endpoints (e.g., AWS IMDS 169.254.169.254).

Patches

v1.19.3

Workarounds

If an immediate upgrade is not possible, users are strongly advised to apply the following mitigations:

  1. Avoid Dynamic Hostnames

    • Do not use the placeholder in the endpoint parameter as hostname.

  2. Restrict Network Access

    • Use firewall rules (e.g., iptables, AWS Security Groups) to block the Fluentd node from accessing sensitive internal IP addresses, specifically the cloud provider's metadata service and other internal microservices that Fluentd does not explicitly need to access.

  3. Restrict allowed hosts

    • Inject filter to accept allowed hosts in placeholders explicitly if possible.
Risk Scores
Base Score
7.2

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the availability of the system.

Threat Intelligence
6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.31%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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