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Vulnerability details: VCID-k4xv-x1pt-guce
Vulnerability ID VCID-k4xv-x1pt-guce
Aliases CVE-2026-4636
GHSA-f2hx-5fx3-hmcv
Summary A flaw was found in Keycloak. An authenticated user with the uma_protection role can bypass User-Managed Access (UMA) policy validation. This allows the attacker to include resource identifiers owned by other users in a policy creation request, even if the URL path specifies an attacker-owned resource. Consequently, the attacker gains unauthorized permissions to victim-owned resources, enabling them to obtain a Requesting Party Token (RPT) and access sensitive information or perform unauthorized actions.
Status Published
Exploitability None
Weighted Severity None
Risk None
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-551 Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
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
cvssv3.1 8.1 https://access.redhat.com/errata/RHSA-2026:6475
generic_textual HIGH https://access.redhat.com/errata/RHSA-2026:6475
cvssv3.1 8.1 https://access.redhat.com/errata/RHSA-2026:6476
generic_textual HIGH https://access.redhat.com/errata/RHSA-2026:6476
cvssv3.1 8.1 https://access.redhat.com/errata/RHSA-2026:6477
generic_textual HIGH https://access.redhat.com/errata/RHSA-2026:6477
ssvc Track https://access.redhat.com/errata/RHSA-2026:6477
cvssv3.1 8.1 https://access.redhat.com/errata/RHSA-2026:6478
generic_textual HIGH https://access.redhat.com/errata/RHSA-2026:6478
ssvc Track https://access.redhat.com/errata/RHSA-2026:6478
cvssv3 8.1 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-4636.json
cvssv3.1 8.1 https://access.redhat.com/security/cve/CVE-2026-4636
generic_textual HIGH https://access.redhat.com/security/cve/CVE-2026-4636
ssvc Track https://access.redhat.com/security/cve/CVE-2026-4636
epss 0.00025 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00025 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00027 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00031 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00031 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00031 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00031 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
epss 0.00031 https://api.first.org/data/v1/epss?cve=CVE-2026-4636
cvssv3.1 8.1 https://bugzilla.redhat.com/show_bug.cgi?id=2450251
generic_textual HIGH https://bugzilla.redhat.com/show_bug.cgi?id=2450251
ssvc Track https://bugzilla.redhat.com/show_bug.cgi?id=2450251
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-f2hx-5fx3-hmcv
cvssv3.1 8.1 https://github.com/keycloak/keycloak
generic_textual HIGH https://github.com/keycloak/keycloak
cvssv3.1 8.1 https://github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725
generic_textual HIGH https://github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725
cvssv3.1 8.1 https://github.com/keycloak/keycloak/issues/47717
generic_textual HIGH https://github.com/keycloak/keycloak/issues/47717
cvssv3.1 8.1 https://nvd.nist.gov/vuln/detail/CVE-2026-4636
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2026-4636
Reference id Reference type URL
https://access.redhat.com/errata/RHSA-2026:6475
https://access.redhat.com/errata/RHSA-2026:6476
https://access.redhat.com/errata/RHSA-2026:6477
https://access.redhat.com/errata/RHSA-2026:6478
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-4636.json
https://api.first.org/data/v1/epss?cve=CVE-2026-4636
https://github.com/keycloak/keycloak
https://github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725
https://github.com/keycloak/keycloak/issues/47717
cpe:/a:redhat:build_keycloak:26.4::el9 https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:build_keycloak:26.4::el9
CVE-2026-4636 https://access.redhat.com/security/cve/CVE-2026-4636
CVE-2026-4636 https://nvd.nist.gov/vuln/detail/CVE-2026-4636
GHSA-f2hx-5fx3-hmcv https://github.com/advisories/GHSA-f2hx-5fx3-hmcv
show_bug.cgi?id=2450251 https://bugzilla.redhat.com/show_bug.cgi?id=2450251
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/errata/RHSA-2026:6475
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:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/errata/RHSA-2026:6476
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:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/errata/RHSA-2026:6477
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: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-02T13:13:39Z/ Found at https://access.redhat.com/errata/RHSA-2026:6477
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/errata/RHSA-2026:6478
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: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-02T13:13:39Z/ Found at https://access.redhat.com/errata/RHSA-2026:6478
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-4636.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:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://access.redhat.com/security/cve/CVE-2026-4636
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: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-02T13:13:39Z/ Found at https://access.redhat.com/security/cve/CVE-2026-4636
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://bugzilla.redhat.com/show_bug.cgi?id=2450251
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: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-04-02T13:13:39Z/ Found at https://bugzilla.redhat.com/show_bug.cgi?id=2450251
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N 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:L/PR:L/UI:N/S:U/C:H/I:H/A:N Found at https://github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725
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:L/UI:N/S:U/C:H/I:H/A:N Found at https://github.com/keycloak/keycloak/issues/47717
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:L/UI:N/S:U/C:H/I:H/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-4636
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 0.06675
EPSS Score 0.00025
Published At April 4, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-03T02:48:52.066575+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/4xxx/CVE-2026-4636.json 38.1.0