Security readout for executives and security teams
Plain-English summary
A Moodle Microsoft 365 integration flaw can let an unauthenticated attacker sign in as a user by presenting a forged Teams SSO token. The plugin trusted the token’s user claim without verifying its signature. Successful abuse could expose or alter Moodle data available to that account.
Executive priority
Treat this as an urgent patching item for Moodle environments using Microsoft 365 integration. It can bypass authentication, does not require user interaction, and may grant access as legitimate users. There is no provided evidence of active exploitation, but the impact justifies rapid remediation.
Technical view
In local_o365 before 4.5.6, 5.0.5, and 5.1.1, sso_login.php base64-decodes a JWT payload and authenticates from the upn claim without signature verification. This is CWE-347 and is scored CVSS 4.0 9.3, network reachable, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is likely limited to Moodle deployments using Microsoft Office 365 Integration plugin local_o365 in affected ranges: below 4.5.6, 5.0.0 to below 5.0.5, or 5.1.0 to below 5.1.1. Risk is highest where the Teams SSO endpoint is reachable by unauthenticated users.
Exploitation context
The source bundle says KEV is false and provides no cited evidence of active exploitation. The vulnerability is still high urgency because the described path is unauthenticated, network reachable, and directly creates a Moodle session as an O365-authenticated user.
Researcher notes
Focus validation on version exposure and reachable Teams SSO surfaces. The key defect is signature trust failure in JWT handling, not a broader Microsoft Entra weakness. Avoid assuming compromise from the CVE alone; corroborate with logs, session records, and affected plugin deployment data.
Mitigation direction
- Upgrade local_o365 4.5.x deployments to 4.5.6 or later.
- Upgrade local_o365 5.0.x deployments to 5.0.5 or later.
- Upgrade local_o365 5.1.x deployments to 5.1.1 or later.
- Review Microsoft’s advisory and release notes for any branch-specific guidance.
- Prioritize externally reachable Moodle sites using Teams SSO.
Validation and detection
- Inventory Moodle sites for the Microsoft 365 and Entra ID plugins.
- Check installed local_o365 versions against the affected ranges.
- Confirm the fixed release is deployed on every active Moodle instance.
- Review Moodle authentication logs for unusual O365-authenticated logins near disclosure.
- Verify Teams SSO behavior still works after upgrading.
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-347: 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 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-2026-54733 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
- 9.3 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA: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
1 official scoreWe 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:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——GitHub_MVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
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
- https://github.com/microsoft/o365-moodle/security/advisories/GHSA-hqjh-93qv-47v5CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/microsoft/o365-moodle/commit/01b2d4c2e13b06a66557527084cbf9bace655944CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/microsoft/o365-moodle/commit/258872f6e2011f4efa8ebb77d2898142a9435e89CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/microsoft/o365-moodle/commit/d5596655f0baaee0f11aec2e10d6f36b0bd29220CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m405CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m500CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/microsoft/o365-moodle/releases/tag/v20260423_m501CVE reference, GitHub_M · x_refsource_MISC
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.
Improper Verification of Cryptographic Signature
Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.