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Vulnerability details: VCID-d65g-gade-ckd5
Vulnerability ID VCID-d65g-gade-ckd5
Aliases CVE-2021-3754
GHSA-4vc8-pg5c-vg4x
Summary Keycloak's improper input validation allows using email as username Keycloak allows the use of email as a username and doesn't check that an account with this email already exists. That could lead to the unability to reset/login with email for the user. This is caused by usernames being evaluated before emails.
Status Published
Exploitability 0.5
Weighted Severity 4.8
Risk 2.4
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-670 Always-Incorrect Control Flow Implementation
CWE-20 Improper Input Validation
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 3.7 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3754.json
cvssv3.1 3.7 https://access.redhat.com/security/cve/CVE-2021-3754
generic_textual LOW https://access.redhat.com/security/cve/CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
epss 0.04922 https://api.first.org/data/v1/epss?cve=CVE-2021-3754
cvssv3.1 3.7 https://bugzilla.redhat.com/show_bug.cgi?id=1999196
generic_textual LOW https://bugzilla.redhat.com/show_bug.cgi?id=1999196
cvssv3.1_qr LOW https://github.com/advisories/GHSA-4vc8-pg5c-vg4x
cvssv3.1 3.7 https://github.com/keycloak/keycloak
generic_textual LOW https://github.com/keycloak/keycloak
cvssv3.1 3.7 https://github.com/keycloak/keycloak/commit/f9708037383aa98741e4850447de64dc4a0d4b4e
generic_textual LOW https://github.com/keycloak/keycloak/commit/f9708037383aa98741e4850447de64dc4a0d4b4e
cvssv3.1 3.7 https://github.com/keycloak/keycloak/security/advisories/GHSA-4vc8-pg5c-vg4x
cvssv3.1_qr LOW https://github.com/keycloak/keycloak/security/advisories/GHSA-4vc8-pg5c-vg4x
generic_textual LOW https://github.com/keycloak/keycloak/security/advisories/GHSA-4vc8-pg5c-vg4x
cvssv3.1 3.7 https://nvd.nist.gov/vuln/detail/CVE-2021-3754
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-3754
generic_textual LOW https://nvd.nist.gov/vuln/detail/CVE-2021-3754
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3754.json
https://access.redhat.com/security/cve/CVE-2021-3754
https://api.first.org/data/v1/epss?cve=CVE-2021-3754
https://bugzilla.redhat.com/show_bug.cgi?id=1999196
https://github.com/keycloak/keycloak
https://github.com/keycloak/keycloak/commit/f9708037383aa98741e4850447de64dc4a0d4b4e
https://github.com/keycloak/keycloak/security/advisories/GHSA-4vc8-pg5c-vg4x
https://nvd.nist.gov/vuln/detail/CVE-2021-3754
cpe:2.3:a:redhat:keycloak:-:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:keycloak:-:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*
GHSA-4vc8-pg5c-vg4x https://github.com/advisories/GHSA-4vc8-pg5c-vg4x
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-3754.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://access.redhat.com/security/cve/CVE-2021-3754
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://bugzilla.redhat.com/show_bug.cgi?id=1999196
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/keycloak/keycloak
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/keycloak/keycloak/commit/f9708037383aa98741e4850447de64dc4a0d4b4e
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/keycloak/keycloak/security/advisories/GHSA-4vc8-pg5c-vg4x
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-3754
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-3754
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.89206
EPSS Score 0.04922
Published At Aug. 7, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:34:35.731836+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/06/GHSA-4vc8-pg5c-vg4x/GHSA-4vc8-pg5c-vg4x.json 37.0.0