Vulnerability-Lookup

CVE-2026-23511 (GCVE-0-2026-23511)

Vulnerability from cvelistv5 – Published: 2026-01-15 19:09 – Updated: 2026-01-15 19:56

Title

ZITADEL has a user enumeration vulnerability in Login UIs

Summary

ZITADEL is an open source identity management platform. Prior to 4.9.1 and 3.4.6, a user enumeration vulnerability has been discovered in Zitadel's login interfaces. An unauthenticated attacker can exploit this flaw to confirm the existence of valid user accounts by iterating through usernames and userIDs. This vulnerability is fixed in 4.9.1 and 3.4.6.

Severity ?

5.3 (Medium)


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

CWE

CWE-204 - Observable Response Discrepancy

Assigner

GitHub_M

References

URL

Tags

	https://github.com/zitadel/zitadel/security/advis…	x_refsource_CONFIRM
	https://github.com/zitadel/zitadel/commit/b85ab69…	x_refsource_MISC
	https://github.com/zitadel/zitadel/commit/c300d4c…	x_refsource_MISC
	https://github.com/zitadel/zitadel/releases/tag/v3.4.6	x_refsource_MISC
	https://github.com/zitadel/zitadel/releases/tag/v4.9.1	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	zitadel	zitadel	Affected: >= 4.0.0, < 4.9.1 Affected: < 3.4.6

Show details on NVD website

JSON

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FKIE_CVE-2026-23511

Vulnerability from fkie_nvd - Published: 2026-01-15 20:16 - Updated: 2026-01-20 16:44

Severity ?

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

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/zitadel/zitadel/commit/b85ab69e4679b0268e2b0e9b4cd04e934af10dd2	Patch
security-advisories@github.com	https://github.com/zitadel/zitadel/commit/c300d4cc6a2775ab17ddfe76492f24170f8b858d	Patch
security-advisories@github.com	https://github.com/zitadel/zitadel/releases/tag/v3.4.6	Release Notes
security-advisories@github.com	https://github.com/zitadel/zitadel/releases/tag/v4.9.1	Release Notes
security-advisories@github.com	https://github.com/zitadel/zitadel/security/advisories/GHSA-pvm5-9frx-264r	Third Party Advisory

Impacted products

Vendor	Product	Version
zitadel	zitadel	*
zitadel	zitadel	*
zitadel	zitadel	*

JSON

To clipboard

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GHSA-PVM5-9FRX-264R

Vulnerability from github – Published: 2026-01-15 18:17 – Updated: 2026-01-21 16:55

Summary

Zitadel has a user enumeration vulnerability in Login UIs

Details

Summary

A user enumeration vulnerability has been discovered in Zitadel's login interfaces. An unauthenticated attacker can exploit this flaw to confirm the existence of valid user accounts by iterating through usernames and userIDs.

Impact

The login UIs (in version 1 and 2) provide the possibility to request a password reset, where an email will be sent to the user with a link to a verification endpoint. By submitting arbitrary userIDs to these endpoints, an attacker can differentiate between valid and invalid accounts based on the system's response.

For an effective exploit the attacker needs to iterate through the potential set of userIDs. The impact can be limited by implementing rate limiting or similar measures to limit enumeration of userIDs.

Additionally, Zitadel includes a security feature "Ignoring unknown usernames", designed to prevent username enumeration attacks by presenting a generic response for both valid and invalid usernames on the login page. The login UI V2 did not handle the setting correctly and would allow attackers to enumerate through usernames to check their existence.

Affected Versions

All versions within the following ranges, including release candidates (RCs), are affected: - v4.x: 4.0.0 through 4.9.0 - 3.x: 3.0.0 through 3.4.5 - 2.x: 2.0.0 through 2.71.19

Patches

The vulnerability has been addressed in the latest releases. The patch resolves the issue by returning a generic error message, which does not indicate it the user exists.

4.x: Upgrade to >=4.9.1 3.x: Update to >=3.4.6 2.x: Update to >=3.4.6

Workarounds

The recommended solution is to update ZITADEL to a patched version. You can limit the impact by implementing rate limiting or similar measures to limit enumeration of userIDs.

There is no workaround for the "Ignoring unknown usernames" issue in login V2. Please upgrade to a patched version, if you rely on this feature.

Questions

If you have any questions or comments about this advisory, please email us at security@zitadel.com

Credits

Thanks to Niklas Kunz from Seamly for reporting this vulnerability from their pentest.

Severity ?

5.3 (Medium)


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

Show details on source website

JSON

To clipboard

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      },
      "package": {
        "ecosystem": "Go",
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    "nvd_published_at": "2026-01-15T20:16:05Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nA user enumeration vulnerability has been discovered in Zitadel\u0027s login interfaces. An unauthenticated attacker can exploit this flaw to confirm the existence of valid user accounts by iterating through usernames and userIDs.\n\n### Impact\n\nThe login UIs (in version 1 and 2) provide the possibility to request a password reset, where an email will be sent to the user with a link to a verification endpoint.\nBy submitting arbitrary userIDs to these endpoints, an attacker can differentiate between valid and invalid accounts based on the system\u0027s response.\n\nFor an effective exploit the attacker needs to iterate through the potential set of userIDs. The impact can be limited by implementing [rate limiting](https://zitadel.com/docs/self-hosting/manage/production#limits-and-quotas) or similar measures to limit enumeration of userIDs.\n\nAdditionally, Zitadel includes a security feature \"Ignoring unknown usernames\", designed to prevent username enumeration attacks by presenting a generic response for both valid and invalid usernames on the login page. The login UI V2 did not handle the setting correctly and would allow attackers to enumerate through usernames to check their existence.\n\n### Affected Versions\n\nAll versions within the following ranges, including release candidates (RCs), are affected:\n- **v4.x**: `4.0.0` through `4.9.0`\n- **3.x**: `3.0.0` through `3.4.5`\n- **2.x**: `2.0.0` through `2.71.19`\n\n### Patches\n\nThe vulnerability has been addressed in the latest releases. The patch resolves the issue by returning a generic error message, which does not indicate it the user exists.\n\n4.x: Upgrade to \u003e=[4.9.1](https://github.com/zitadel/zitadel/releases/tag/v4.9.1)\n3.x: Update to \u003e=[3.4.6](https://github.com/zitadel/zitadel/releases/tag/v3.4.6)\n2.x: Update to \u003e=[3.4.6](https://github.com/zitadel/zitadel/releases/tag/v3.4.6)\n\n### Workarounds\n\nThe recommended solution is to update ZITADEL to a patched version. You can limit the impact by implementing [rate limiting](https://zitadel.com/docs/self-hosting/manage/production#limits-and-quotas) or similar measures to limit enumeration of userIDs.\n\nThere is no workaround for the \"Ignoring unknown usernames\" issue in login V2. Please upgrade to a patched version, if you rely on this feature.\n\n### Questions\n\nIf you have any questions or comments about this advisory, please email us at [security@zitadel.com](mailto:security@zitadel.com)\n\n### Credits\n\nThanks to Niklas Kunz from Seamly for reporting this vulnerability from their pentest.",
  "id": "GHSA-pvm5-9frx-264r",
  "modified": "2026-01-21T16:55:10Z",
  "published": "2026-01-15T18:17:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/security/advisories/GHSA-pvm5-9frx-264r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23511"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/commit/0bb00dd9fc4e5e965f8e14fa2161a5076f3c308d"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/commit/b85ab69e4679b0268e2b0e9b4cd04e934af10dd2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/commit/c300d4cc6a2775ab17ddfe76492f24170f8b858d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/zitadel/zitadel"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/releases/tag/v3.4.6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zitadel/zitadel/releases/tag/v4.9.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Zitadel has a user enumeration vulnerability in Login UIs"
}

Sightings

Author	Source	Type	Date

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.

Action not permitted

CVE-2026-23511 (GCVE-0-2026-23511)

FKIE_CVE-2026-23511

GHSA-PVM5-9FRX-264R

Summary

Impact

Affected Versions

Patches

Workarounds

Questions

Credits

Tags

Sightings

Nomenclature