CVE-2024-56136Network attack vector

Email-account enumeration via invalid-subdomain error

Published Jan 16, 2025 · Updated Feb 6, 2025

Information disclosure in Zulip Server 7.0 through 9.3 allows remote attackers to determine whether an email address has a server account. The API-key authentication failure path returns a distinct invalid-subdomain error when the address exists in another organization instead of the generic error used for other failed logins. No authentication is required, but the server must host multiple organizations; single-organization deployments are unaffected.

CVSS severity6.9
Medium
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Zulip Server 7.0 through 9.3 allows remote attackers to determine whether an email address has a server account. The API-key authentication failure path returns a distinct invalid-subdomain error when the address exists in another organization instead of the generic error used for other failed logins. No authentication is required, but the server must host multiple organizations; single-organization deployments are unaffected.

The record

CVE
CVE-2024-56136
Published
Jan 16, 2025
Updated
Feb 6, 2025
Vendor
Zulip
Product
Zulip
Classifications
CWE-200, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2025Record 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=>= 7.0, < 9.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zulip · Zulipversion=>= 7.0, < 9.4

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
5.3NIST NVDCVSS: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-200Exposure of Sensitive Information to an Unauthorized Actor
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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