Security readout for executives and security teams
Plain-English summary
CVE-2026-3872 is a Keycloak redirect handling flaw that can let an attacker redirect authentication results to a path they control on the same web server. If successful, an access token may be stolen, exposing protected information and potentially allowing account-level actions tied to that token.
Executive priority
Treat as high priority for identity platforms because token theft can affect confidentiality and downstream access. Prioritize internet-facing or multi-tenant Keycloak deployments and environments with wildcard redirect URI patterns.
Technical view
The issue is a redirect_uri validation bypass involving wildcard allowed paths in Red Hat build of Keycloak. It is classified as CWE-601 with CVSS 3.1 score 7.3. Exploitation requires network access, low privileges, user interaction, and control of another path on the same web server.
Likely exposure
Exposure is most likely in Red Hat build of Keycloak 26.2 or 26.4 deployments using wildcard redirect URIs where another party controls a sibling path on the same web server.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. The described attack depends on a specific redirect configuration, attacker control of another same-server path, and user interaction during an authentication flow.
Researcher notes
Evidence is strongest for affected Red Hat build of Keycloak packages and the redirect_uri wildcard path bypass. Public details in the bundle do not establish exploit availability, active exploitation, or non-Red Hat product impact.
Mitigation direction
- Review Red Hat advisories RHSA-2026:6475 through RHSA-2026:6478 for applicable fixed builds.
- Update affected Red Hat build of Keycloak packages according to Red Hat guidance.
- Avoid broad wildcard redirect URIs for sensitive clients where possible.
- Restrict who can create or control paths on authentication callback web servers.
- Review client redirect_uri allowlists for unnecessary wildcards.
Validation and detection
- Inventory Red Hat build of Keycloak 26.2 and 26.4 deployments.
- Compare installed package versions against Red Hat CVE and CSAF VEX data.
- Identify clients using wildcard redirect URIs.
- Check whether untrusted users control any same-server paths matching wildcard scope.
- Review authentication logs for unusual redirects or unexpected callback paths.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-601: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-3872 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N2.15.2redhatCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N2.15.2redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- ADP timelineredhat-SADP
Reported to Red Hat.
- Source timelineredhat
Reported to Red Hat.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- Source timelineredhat
Made public.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-03-10T09:16:29.034Z: Reported to Red Hat.
- 2026-04-02T12:30:00.000Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- RHSA-2026:6475CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6476CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6477CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6478CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-3872CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2445988CVE reference, redhat · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3872.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
URL Redirection to Untrusted Site ('Open Redirect')
URL Redirection to Untrusted Site ('Open Redirect') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.