CVE-2026-23511Network attack vector

Unauthenticated user enumeration via discrepant login responses

Published Jan 15, 2026 · Updated Jan 15, 2026

User enumeration in ZITADEL before 3.4.6 and 4.0.0 through 4.9.0 allows remote attackers to confirm valid accounts via login requests. Login V1 recovery and verification handlers return account-dependent errors for submitted user IDs, while Login V2 mishandles the ignore-unknown-user setting for usernames. Exploitation requires iterating candidate identifiers; it discloses account existence without reported access to account data.

CVSS severity5.3
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

User enumeration in ZITADEL before 3.4.6 and 4.0.0 through 4.9.0 allows remote attackers to confirm valid accounts via login requests. Login V1 recovery and verification handlers return account-dependent errors for submitted user IDs, while Login V2 mishandles the ignore-unknown-user setting for usernames. Exploitation requires iterating candidate identifiers; it discloses account existence without reported access to account data.

The record

CVE
CVE-2026-23511
Published
Jan 15, 2026
Updated
Jan 15, 2026
Vendor
ZITADEL
Product
ZITADEL
Classifications
CWE-204, T1087
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.4.6
  2. Affected versionversion=>= 4.0.0, < 4.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ZITADEL · ZITADELversion=< 3.4.6; version=>= 4.0.0, < 4.9.1

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-204Observable Response Discrepancy
T1087Account Discovery

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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