Security readout for executives and security teams
Plain-English summary
CVE-2026-56400 lets a malicious website abuse an authenticated Open WebUI administrator's browser to trigger code execution on the Open WebUI server. The issue is critical because compromise affects the application host, but the attacker needs administrator interaction and a vulnerable Open WebUI version before 0.3.14.
Executive priority
Treat this as urgent for any Open WebUI deployment used by administrators. The impact is server-side code execution, but exploitation depends on administrator browser interaction. Prioritize version verification, upgrade planning, and access reduction for externally reachable instances.
Technical view
Open WebUI before 0.3.14 allowed arbitrary CORS origins while accepting authenticated requests to /api/v1/functions. With an admin session present, cross-site requests from an attacker-controlled site could reach that endpoint and execute code on the Open WebUI instance. The CVSS 4.0 score is 9.0, with network attack vector and user interaction required.
Likely exposure
Exposure is limited to organizations running Open WebUI versions before 0.3.14 where administrators access the service through browsers with active sessions. Internet-facing or broadly reachable admin interfaces increase business risk. The source bundle does not provide deployment prevalence or exposed-instance counts.
Exploitation context
The sources describe a malicious-site scenario requiring an administrator to visit attacker-controlled content while authenticated. The CVE is not listed as KEV in the bundle, and no provided source states active exploitation in the wild.
Researcher notes
The public bundle attributes the flaw to CORS misconfiguration and insufficient session validation around /api/v1/functions. Evidence supports critical severity and a cross-site authenticated request path, but it does not include exploit telemetry, patch details beyond the affected-version boundary, or environmental indicators.
Mitigation direction
- Upgrade Open WebUI beyond the affected pre-0.3.14 range using vendor guidance.
- Restrict CORS to trusted origins; do not allow arbitrary origins for authenticated admin APIs.
- Limit administrator access to trusted networks or access controls where feasible.
- Review active admin sessions and reset them after remediation.
- Monitor Open WebUI function activity for unexpected administrator-triggered changes.
Validation and detection
- Inventory Open WebUI deployments and confirm their exact running versions.
- Check whether any deployment is older than 0.3.14.
- Review CORS configuration for wildcard origins on authenticated routes.
- Confirm /api/v1/functions is not reachable from untrusted browser origins.
- Review logs for unusual function changes around admin browsing sessions.
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-613: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-56400 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
- Critical
- CVSS
- 9 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
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:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H——VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H1.66VulnCheckVulnerability scoring details
Base CVSS 4.0 score
9CriticalVector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Base CVSS 3.1 score
8.3HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- 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
Source materials
- CVE List V5 sourceCVE List V5
- GitHub Security Advisory (GHSA-6xcp-7mpr-m7wm)CVE reference, VulnCheck · vendor-advisory
- VulnCheck Advisory: open-webui - Remote Code Execution via CORS Misconfiguration and Session ValidationCVE reference, VulnCheck · third-party-advisory
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.
Insufficient Session Expiration
Insufficient Session Expiration represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.