Medium

CVE-2024-0391 — Username Enumeration via Email OTP Flow in Multiple WSO2 Products Allows User Account Discovery

The check user account lock states feature within the email OTP flow fails to validate user input, allowing an attacker to infer the existence of registered user accounts. The discovery of valid usernames can increase the risk of brute-force and social engineering attacks. Attackers can leverage this information to craft targeted phishing campaigns or other malicious activities aimed at tricking users into divulging sensitive data, potentially damaging the organization's reputation and leading to regulatory non-compliance and financial consequences.

Published May 11, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: WSO2

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.18%

ahead of 7% of scored CVEs · Oct 14, 2026

Affects

WSO2

Email OTP Authenticator and 4 more

CVSS base

4.3

Medium · 3 source(s)

Prioritization reference: 5.3 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (WSO2 Email OTP Authenticator, WSO2 Identity Server, WSO2 Identity Server As Key Manager…).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
WSO2	Email OTP Authenticator	≥ 1.0.18 and < 1.0.18.7	Vulnerable	CVE Program (cve.org) e CISA ADP
WSO2	Identity Server	≥ 5.11.0 and < 5.11.0.426≥ 7.0.0 and < 7.0.0.131≥ 6.1.0 and < 6.1.0.254≥ 6.0.0 and < 6.0.0.253≥ 5.10.0 and < 5.10.0.379	Vulnerable	NIST National Vulnerability Database
WSO2	Identity Server	≥ 7.0.0 and < 7.0.0.131≥ 6.1.0 and < 6.1.0.254≥ 6.0.0 and < 6.0.0.253≥ 5.11.0 and < 5.11.0.431≥ 5.11.0 and < 5.11.0.426≥ 5.10.0 and < 5.10.0.379	Vulnerable	CVE Program (cve.org) e CISA ADP
WSO2	Identity Server As Key Manager	≥ 5.10.0 and < 5.10.267	Vulnerable	NIST National Vulnerability Database
WSO2	Identity Server As Key Manager	≥ 5.10.0 and < 5.10.0.267	Vulnerable	CVE Program (cve.org) e CISA ADP
WSO2	Open Banking Iam	≥ 2.0.0 and < 2.0.0.318	Vulnerable	NIST National Vulnerability Database
WSO2	Open Banking Iam	≥ 2.0.0 and < 2.0.0.318	Vulnerable	CVE Program (cve.org) e CISA ADP
WSO2	WSO2 Carbon Authenticator Library For EmailOTP	≥ 4.1.0 and < 4.1.0.8≥ 4.1.4 and < 4.1.4.9≥ 3.0.5 and < 3.0.5.8≥ 3.0.24 and < 3.0.24.6≥ 3.0.26 and < 3.0.26.16	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 3.1	Medium	3.9	1.4	ed10eef1-636d-4fbe-9993-6890dfa878f8 via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	—	—	WSO2 via CVE Program (cve.org) e CISA ADP
4.3	CVSS 3.1	Medium	2.8	1.4	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 5.3 (ed10eef1-636d-4fbe-9993-6890dfa878f8 via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-204

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.18%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · wso2/wso2 identity server, wso2/wso2 open banking iam, wso2/wso2 identity server as key manager, wso2/email otp authenti
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 4.3
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 11, 2026 · WSO2

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2024-3
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database

Elsewhere on this site

WSO2
every CVE for this vendor

CWE-204
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2024-8122 Potential brute force vulnerability due to non-expiring SMS OTPs 7d
Low CVE-2025-13166 Username Enumeration via SMS OTP Flow in WSO2 Identity Server Allows User Account Discovery Sep 15, 2026
Medium CVE-2026-0637 Insertion of Sensitive Information into Log File in WSO2 Api Control Plane Aug 6, 2026
Critical CVE-2025-15039 The Conditional Authentication (Adaptive Authentication) script does not correctly… Aug 6, 2026
Low CVE-2025-13736 Observable Discrepancy in WSO2 Api Manager Aug 6, 2026
Medium CVE-2025-13909 Improper Input Validation in WSO2 Identity Server Aug 6, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2024-0391 is "Username Enumeration via Email OTP Flow in Multiple WSO2 Products Allows User Account Discovery", rated Medium. It affects Email OTP Authenticator (WSO2); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.3 describes technical severity. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.