Vulnerability-Lookup

CVE-2026-20915 (GCVE-0-2026-20915)

Vulnerability from cvelistv5 – Published: 2026-03-31 13:51 – Updated: 2026-03-31 17:15

Title

Stored cross-site scripting in Pending Changes sidebar

Summary

Stored cross-site scripting (XSS) in Checkmk version 2.5.0 (beta) before 2.5.0b2 allows authenticated users with permission to create pending changes to inject malicious JavaScript into the Pending Changes sidebar, which will execute in the browsers of other users viewing the sidebar.

Severity

8.5 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

Checkmk

References

1 reference

URL	Tags
https://checkmk.com/werk/19526	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
Checkmk GmbH	Checkmk	Affected: 2.5.0b1 , < 2.5.0b2 (semver)

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-20915

Vulnerability from fkie_nvd - Published: 2026-03-31 15:16 - Updated: 2026-06-17 10:18

Severity

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

Summary

References

	URL	Tags
	security@checkmk.com	https://checkmk.com/werk/19526	Vendor Advisory

Impacted products

	Vendor	Product	Version
	checkmk	checkmk	2.5.0

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Checkmk",
          "vendor": "Checkmk GmbH",
          "versions": [
            {
              "lessThan": "2.5.0b2",
              "status": "affected",
              "version": "2.5.0b1",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "security@checkmk.com"
    }
  ],
  "configurations": [
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    }
  ],
  "id": "CVE-2026-20915",
  "lastModified": "2026-06-17T10:18:01.467",
  "metrics": {
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        "cvssData": {
          "attackComplexity": "LOW",
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          "integrityImpact": "LOW",
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          "scope": "CHANGED",
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GHSA-C37F-QCH7-R2CG

Vulnerability from github – Published: 2026-03-31 15:31 – Updated: 2026-04-02 12:31

Details

Severity

5.4 (Medium)


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

8.5 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-20915"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-31T15:16:11Z",
    "severity": "HIGH"
  },
  "details": "Stored cross-site scripting (XSS) in Checkmk version 2.5.0 (beta) before 2.5.0b2 allows authenticated users with permission to create pending changes to inject malicious JavaScript into the Pending Changes sidebar, which will execute in the browsers of other users viewing the sidebar.",
  "id": "GHSA-c37f-qch7-r2cg",
  "modified": "2026-04-02T12:31:05Z",
  "published": "2026-03-31T15:31:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-20915"
    },
    {
      "type": "WEB",
      "url": "https://checkmk.com/werk/19526"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

ubuntu-cve-2026-20915

Vulnerability from osv_ubuntu

Published

2026-03-31 15:16

Modified

2026-04-13 09:31

Summary

Details

Severity

8.5 (High)


                    
                      CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N

5.4 (Medium)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-20915	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-20915	REPORT
	https://checkmk.com/werk/19526	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "check-mk-agent",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-agent-logwatch",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-config-icinga",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-config-nagios3",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-livestatus",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-multisite",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          },
          {
            "binary_name": "check-mk-server",
            "binary_version": "1.2.6p12-1ubuntu0.16.04.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "check-mk",
        "purl": "pkg:deb/ubuntu/check-mk@1.2.6p12-1ubuntu0.16.04.1+esm1?arch=source\u0026distro=esm-apps/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.6p5-1",
        "1.2.6p12-1",
        "1.2.6p12-1ubuntu0.16.04.1",
        "1.2.6p12-1ubuntu0.16.04.1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "check-mk-agent",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          },
          {
            "binary_name": "check-mk-agent-logwatch",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          },
          {
            "binary_name": "check-mk-config-icinga",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          },
          {
            "binary_name": "check-mk-livestatus",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          },
          {
            "binary_name": "check-mk-multisite",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          },
          {
            "binary_name": "check-mk-server",
            "binary_version": "1.2.8p16-1ubuntu0.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "check-mk",
        "purl": "pkg:deb/ubuntu/check-mk@1.2.8p16-1ubuntu0.2?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.8p16-1ubuntu0.1",
        "1.2.8p16-1ubuntu0.2"
      ]
    }
  ],
  "aliases": [],
  "details": "Stored cross-site scripting (XSS) in Checkmk version 2.5.0 (beta) before 2.5.0b2 allows authenticated users with permission to create pending changes to inject malicious JavaScript into the Pending Changes sidebar, which will execute in the browsers of other users viewing the sidebar.",
  "id": "UBUNTU-CVE-2026-20915",
  "modified": "2026-04-13T09:31:27Z",
  "published": "2026-03-31T15:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-20915"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-20915"
    },
    {
      "type": "REPORT",
      "url": "https://checkmk.com/werk/19526"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-20915"
  ]
}

WID-SEC-W-2026-0928

Vulnerability from csaf_certbund - Published: 2026-03-30 22:00 - Updated: 2026-03-31 22:00

Summary

Checkmk: Mehrere Schwachstellen ermöglichen Cross-Site Scripting

Severity

Hoch

Notes

Das BSI ist als Anbieter für die eigenen, zur Nutzung bereitgestellten Inhalte nach den allgemeinen Gesetzen verantwortlich. Nutzerinnen und Nutzer sind jedoch dafür verantwortlich, die Verwendung und/oder die Umsetzung der mit den Inhalten bereitgestellten Informationen sorgfältig im Einzelfall zu prüfen.

Produktbeschreibung: Checkmk ist eine IT-Monitoring-Software.

Angriff: Ein Angreifer kann mehrere Schwachstellen in Checkmk ausnutzen, um einen Cross-Site Scripting Angriff durchzuführen.

Betroffene Betriebssysteme: - Linux - UNIX

CVE-2026-20915

Affected products

Known affected 2 products

Product	Identifier	Version	Remediation
Checkmk Checkmk <2.5.0b2 Checkmk / Checkmk		<2.5.0b2
Checkmk Checkmk <2.6.0b1 Checkmk / Checkmk		<2.6.0b1

CVE-2026-33276

Affected products

Known affected 2 products

Product	Identifier	Version	Remediation
Checkmk Checkmk <2.5.0b2 Checkmk / Checkmk		<2.5.0b2
Checkmk Checkmk <2.6.0b1 Checkmk / Checkmk		<2.6.0b1

References

4 references

URL	Category
https://wid.cert-bund.de/.well-known/csaf/white/2…	self
https://wid.cert-bund.de/portal/wid/securityadvis…	self
https://checkmk.com/werk/19525	external
https://checkmk.com/werk/19526	external

JSON

To clipboard

{
  "document": {
    "aggregate_severity": {
      "text": "hoch"
    },
    "category": "csaf_base",
    "csaf_version": "2.0",
    "distribution": {
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "de-DE",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "Das BSI ist als Anbieter f\u00fcr die eigenen, zur Nutzung bereitgestellten Inhalte nach den allgemeinen Gesetzen verantwortlich. Nutzerinnen und Nutzer sind jedoch daf\u00fcr verantwortlich, die Verwendung und/oder die Umsetzung der mit den Inhalten bereitgestellten Informationen sorgf\u00e4ltig im Einzelfall zu pr\u00fcfen."
      },
      {
        "category": "description",
        "text": "Checkmk ist eine IT-Monitoring-Software.",
        "title": "Produktbeschreibung"
      },
      {
        "category": "summary",
        "text": "Ein Angreifer kann mehrere Schwachstellen in Checkmk ausnutzen, um einen Cross-Site Scripting Angriff durchzuf\u00fchren.",
        "title": "Angriff"
      },
      {
        "category": "general",
        "text": "- Linux\n- UNIX",
        "title": "Betroffene Betriebssysteme"
      }
    ],
    "publisher": {
      "category": "other",
      "contact_details": "csaf-provider@cert-bund.de",
      "name": "Bundesamt f\u00fcr Sicherheit in der Informationstechnik",
      "namespace": "https://www.bsi.bund.de"
    },
    "references": [
      {
        "category": "self",
        "summary": "WID-SEC-W-2026-0928 - CSAF Version",
        "url": "https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0928.json"
      },
      {
        "category": "self",
        "summary": "WID-SEC-2026-0928 - Portal Version",
        "url": "https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-0928"
      },
      {
        "category": "external",
        "summary": "CheckMK Werk  19525 vom 2026-03-30",
        "url": "https://checkmk.com/werk/19525"
      },
      {
        "category": "external",
        "summary": "CheckMK Werk 19526 vom 2026-03-30",
        "url": "https://checkmk.com/werk/19526"
      }
    ],
    "source_lang": "en-US",
    "title": "Checkmk: Mehrere Schwachstellen erm\u00f6glichen Cross-Site Scripting",
    "tracking": {
      "current_release_date": "2026-03-31T22:00:00.000+00:00",
      "generator": {
        "date": "2026-04-01T09:22:36.428+00:00",
        "engine": {
          "name": "BSI-WID",
          "version": "1.5.0"
        }
      },
      "id": "WID-SEC-W-2026-0928",
      "initial_release_date": "2026-03-30T22:00:00.000+00:00",
      "revision_history": [
        {
          "date": "2026-03-30T22:00:00.000+00:00",
          "number": "1",
          "summary": "Initiale Fassung"
        },
        {
          "date": "2026-03-31T22:00:00.000+00:00",
          "number": "2",
          "summary": "Referenz(en) aufgenommen: EUVD-2026-17417, EUVD-2026-17429"
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003c2.6.0b1",
                "product": {
                  "name": "Checkmk Checkmk \u003c2.6.0b1",
                  "product_id": "T052303"
                }
              },
              {
                "category": "product_version",
                "name": "2.6.0b1",
                "product": {
                  "name": "Checkmk Checkmk 2.6.0b1",
                  "product_id": "T052303-fixed",
                  "product_identification_helper": {
                    "cpe": "cpe:/a:checkmk:checkmk:2.6.0b1"
                  }
                }
              },
              {
                "category": "product_version_range",
                "name": "\u003c2.5.0b2",
                "product": {
                  "name": "Checkmk Checkmk \u003c2.5.0b2",
                  "product_id": "T052304"
                }
              },
              {
                "category": "product_version",
                "name": "2.5.0b2",
                "product": {
                  "name": "Checkmk Checkmk 2.5.0b2",
                  "product_id": "T052304-fixed",
                  "product_identification_helper": {
                    "cpe": "cpe:/a:checkmk:checkmk:2.5.0b2"
                  }
                }
              }
            ],
            "category": "product_name",
            "name": "Checkmk"
          }
        ],
        "category": "vendor",
        "name": "Checkmk"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-20915",
      "product_status": {
        "known_affected": [
          "T052304",
          "T052303"
        ]
      },
      "release_date": "2026-03-30T22:00:00.000+00:00",
      "title": "CVE-2026-20915"
    },
    {
      "cve": "CVE-2026-33276",
      "product_status": {
        "known_affected": [
          "T052304",
          "T052303"
        ]
      },
      "release_date": "2026-03-30T22:00:00.000+00:00",
      "title": "CVE-2026-33276"
    }
  ]
}

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

CVE-2026-20915 (GCVE-0-2026-20915)

FKIE_CVE-2026-20915

GHSA-C37F-QCH7-R2CG

ubuntu-cve-2026-20915

Vulnerability from osv_ubuntu

WID-SEC-W-2026-0928

Tags

Sightings

Nomenclature