Vulnerability-Lookup

CVE-2026-44163 (GCVE-0-2026-44163)

Vulnerability from cvelistv5 – Published: 2026-09-15 15:39 – Updated: 2026-09-16 16:02

Title

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

Summary

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.

Severity

5.3 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-16 16:01 UTC

CWE

CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/fluent-plugins-nursery/fluent-…	x_refsource_CONFIRM
https://github.com/fluent-plugins-nursery/fluent-…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
fluent-plugins-nursery	fluent-plugin-opentelemetry	Affected: < 0.5.3	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44163

Vulnerability from fkie_nvd - Published: 2026-09-15 16:17 - Updated: 2026-09-16 17:17

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Summary

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "fluent-plugin-opentelemetry",
          "vendor": "fluent-plugins-nursery",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.5.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-44163",
  "lastModified": "2026-09-16T17:17:18.673",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-44163",
          "options": [
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            },
            {
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            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-16T16:01:56.034552Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-15T16:17:09.823",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/commit/ce6c1f2a7741592c8a79afbe75fded9e8ebfa92d"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/security/advisories/GHSA-2jc5-xhx8-qj6h"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
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          "value": "CWE-409"
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      "type": "Secondary"
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  ]
}

GHSA-2JC5-XHX8-QJ6H

Vulnerability from github – Published: 2026-06-26 17:22 – Updated: 2026-06-26 17:22

Summary

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

Details

The fluent-plugin-opentelemetry plugin (specifically the in_opentelemetry HTTP input) lacked strict size limits on incoming requests. It was discovered that the plugin read the entire request body and decompressed payloads into memory without enforcing maximum size thresholds.

If the OpenTelemetry ingestion endpoint is exposed to untrusted networks, an attacker can send an excessively large HTTP request or a maliciously crafted, highly compressed payload. When the plugin attempts to read or decompress this payload, it will expand to an excessive size and it will consume significant system resources.

Impact

This vulnerability allows for a Denial of Service (DoS) attack via memory exhaustion. The rapid memory consumption during decompression can easily lead to an Out-of-Memory kill of the Fluentd process by the operating system. This results in the disruption of all log collection and forwarding capabilities on the affected node.

Patches

v0.5.3

Workarounds

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

Restrict Network Access
Ensure that the OpenTelemetry ingestion ports (default 4318) are deployed within a closed, trusted network. Use firewall rules (e.g., iptables, AWS Security Groups) to block access from untrusted networks or instances.
Use a Reverse Proxy
If you must expose HTTP ingestion to external sources, place a robust reverse proxy (such as Nginx) in front of Fluentd. Configure the proxy to handle the gzip decompression and enforce strict limits on both compressed and uncompressed body sizes before passing the traffic to Fluentd.

Severity

5.3 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.5.2"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "fluent-plugin-opentelemetry"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.5.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44163"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T17:22:37Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "The `fluent-plugin-opentelemetry` plugin (specifically the `in_opentelemetry` HTTP input) lacked strict size limits on incoming requests.\nIt was discovered that the plugin read the entire request body and decompressed payloads into memory without enforcing maximum size thresholds.\n\nIf the OpenTelemetry ingestion endpoint is exposed to untrusted networks, an attacker can send an excessively large HTTP request or a maliciously crafted, highly compressed payload.\nWhen the plugin attempts to read or decompress this payload, it will expand to an excessive size and it will consume significant system resources.\n\n### Impact\nThis vulnerability allows for a **Denial of Service (DoS)** attack via memory exhaustion. \nThe rapid memory consumption during decompression can easily lead to an Out-of-Memory kill of the Fluentd process by the operating system.\nThis results in the disruption of all log collection and forwarding capabilities on the affected node.\n\n### Patches\nv0.5.3\n\n### Workarounds\nIf an immediate upgrade is not possible, users are strongly advised to apply the following mitigations:\n\n1. Restrict Network Access\n   * Ensure that the OpenTelemetry ingestion ports (default `4318`) are deployed within a closed, trusted network. Use firewall rules (e.g., iptables, AWS Security Groups) to block access from untrusted networks or instances.\n2. Use a Reverse Proxy\n   * If you must expose HTTP ingestion to external sources, place a robust reverse proxy (such as Nginx) in front of Fluentd. Configure the proxy to handle the gzip decompression and enforce strict limits on both compressed and uncompressed body sizes before passing the traffic to Fluentd.",
  "id": "GHSA-2jc5-xhx8-qj6h",
  "modified": "2026-06-26T17:22:37Z",
  "published": "2026-06-26T17:22:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/security/advisories/GHSA-2jc5-xhx8-qj6h"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry/commit/ce6c1f2a7741592c8a79afbe75fded9e8ebfa92d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fluent-plugins-nursery/fluent-plugin-opentelemetry"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fluent-plugin-opentelemetry Has Denial of Service (DoS) via Large Payloads and Decompression Bombs in `in_opentelemetry`"
}

JVNDB-2026-000090

Vulnerability from jvndb - Published: 2026-06-29 05:18 - Updated:2026-06-29 05:18

Severity

9.8 (Critical) - cvssV3_0 - CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

Multiple vulnerabilities in Fluentd

Details

Fluentd provided by Fluentd Project contains multiple vulnerabilities listed below.

Path traversal in ${tag} Placeholder (CWE-22) - CVE-2026-44024
Missing authentication for critical function in Monitor Agent API (CWE-306) - CVE-2026-44025
Improper handling of highly compressed data in in_http and in_forward (CWE-409) - CVE-2026-44160
Server-side request forgery in out_http (CWE-918) - CVE-2026-44161
Improper handling of highly compressed data in in_s3 (CWE-409) - CVE-2026-44162
Improper handling of highly compressed data in in_opentelemetry (CWE-409) - CVE-2026-44163

The developer reported these vulnerabilities to IPA to notify users of the solutions through JVN. JPCERT/CC and the developer coordinated under the Information Security Early Warning Partnership.

References

Type

URL

	JVN	https://jvn.jp/en/jp/JVN36011274/index.html
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44024
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44025
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44160
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44161
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44162
	CVE	https://www.cve.org/CVERecord?id=CVE-2026-44163
	Path Traversal(CWE-22)	https://www.ipa.go.jp/en/security/vulnerabilities/cwe.html
	No Mapping(CWE-Other)	https://www.ipa.go.jp/en/security/vulnerabilities/cwe.html

Impacted products

Vendor

Product

	ClearCode Inc.	fluent-package
	Fluentd Project	fluent-plugin-opentelemetry
	Fluentd Project	fluent-plugin-s3
	Fluentd Project	Fluentd

Show details on JVN DB website

JSON

To clipboard

{
  "@rdf:about": "https://jvndb.jvn.jp/en/contents/2026/JVNDB-2026-000090.html",
  "dc:date": "2026-06-29T14:18+09:00",
  "dcterms:issued": "2026-06-29T14:18+09:00",
  "dcterms:modified": "2026-06-29T14:18+09:00",
  "description": "Fluentd provided by Fluentd Project contains multiple vulnerabilities listed below.  \u003ca href=\u0027https://cwe.mitre.org/data/definitions/22.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027https://www.cve.org/CVERecord?id=CVE-2026-44024\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027https://cwe.mitre.org/data/definitions/306.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027http://www.cve.org/CVERecord?id=CVE-2026-44025\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e    \u003ca href=\u0027https://cwe.mitre.org/data/definitions/409.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027http://www.cve.org/CVERecord?id=CVE-2026-44160\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e  \u003ca href=\u0027https://cwe.mitre.org/data/definitions/918.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027http://www.cve.org/CVERecord?id=CVE-2026-44161\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e  \u003ca href=\u0027https://cwe.mitre.org/data/definitions/409.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027http://www.cve.org/CVERecord?id=CVE-2026-44162\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e  \u003ca href=\u0027https://cwe.mitre.org/data/definitions/409.html\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003ca href=\u0027http://www.cve.org/CVERecord?id=CVE-2026-44163\u0027 target=\u0027_blank\u0027\u003e\u003c/a\u003e\u003cul\u003e\u003cli\u003ePath traversal in ${tag} Placeholder (CWE-22) - CVE-2026-44024\u003c/li\u003e\u003cli\u003eMissing authentication for critical function in Monitor Agent API (CWE-306) - CVE-2026-44025\u003c/li\u003e\u003cli\u003eImproper handling of highly compressed data in in_http and in_forward  (CWE-409) - CVE-2026-44160\u003c/li\u003e\u003cli\u003eServer-side request forgery in out_http (CWE-918) - CVE-2026-44161\u003c/li\u003e\u003cli\u003eImproper handling of highly compressed data in in_s3 (CWE-409) - CVE-2026-44162\u003c/li\u003e\u003cli\u003eImproper handling of highly compressed data in in_opentelemetry (CWE-409) - CVE-2026-44163\u003c/li\u003e\u003c/ul\u003eThe developer reported these vulnerabilities to IPA to notify users of the solutions through JVN. JPCERT/CC and the developer coordinated under the Information Security Early Warning Partnership.",
  "link": "https://jvndb.jvn.jp/en/contents/2026/JVNDB-2026-000090.html",
  "sec:cpe": [
    {
      "#text": "cpe:/a:misc:clearcode_fluent-package",
      "@product": "fluent-package",
      "@vendor": "ClearCode Inc.",
      "@version": "2.2"
    },
    {
      "#text": "cpe:/a:misc:fluentd_project_fluent-plugin-opentelemetry",
      "@product": "fluent-plugin-opentelemetry",
      "@vendor": "Fluentd Project",
      "@version": "2.2"
    },
    {
      "#text": "cpe:/a:misc:fluentd_project_fluent-plugin-s3",
      "@product": "fluent-plugin-s3",
      "@vendor": "Fluentd Project",
      "@version": "2.2"
    },
    {
      "#text": "cpe:/a:misc:fluentd_project_fluentd",
      "@product": "Fluentd",
      "@vendor": "Fluentd Project",
      "@version": "2.2"
    }
  ],
  "sec:cvss": {
    "@score": "9.8",
    "@severity": "Critical",
    "@type": "Base",
    "@vector": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "@version": "3.0"
  },
  "sec:identifier": "JVNDB-2026-000090",
  "sec:references": [
    {
      "#text": "https://jvn.jp/en/jp/JVN36011274/index.html",
      "@id": "JVN#36011274",
      "@source": "JVN"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44024",
      "@id": "CVE-2026-44024",
      "@source": "CVE"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44025",
      "@id": "CVE-2026-44025",
      "@source": "CVE"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44160",
      "@id": "CVE-2026-44160",
      "@source": "CVE"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44161",
      "@id": "CVE-2026-44161",
      "@source": "CVE"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44162",
      "@id": "CVE-2026-44162",
      "@source": "CVE"
    },
    {
      "#text": "https://www.cve.org/CVERecord?id=CVE-2026-44163",
      "@id": "CVE-2026-44163",
      "@source": "CVE"
    },
    {
      "#text": "https://www.ipa.go.jp/en/security/vulnerabilities/cwe.html",
      "@id": "CWE-22",
      "@title": "Path Traversal(CWE-22)"
    },
    {
      "#text": "https://www.ipa.go.jp/en/security/vulnerabilities/cwe.html",
      "@id": "CWE-Other",
      "@title": "No Mapping(CWE-Other)"
    }
  ],
  "title": "Multiple vulnerabilities in Fluentd"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-44163 (GCVE-0-2026-44163)

FKIE_CVE-2026-44163

GHSA-2JC5-XHX8-QJ6H

Impact

Patches

Workarounds

JVNDB-2026-000090

Tags

Sightings

Nomenclature

Related by attack behaviour