Security readout for executives and security teams
Plain-English summary
An unauthenticated attacker can place malicious content in Chamilo’s registration form. When an administrator later views the stored entry, code can run inside the administrator’s browser session and enable full platform administration takeover. Chamilo 1.11.38 and earlier are affected; version 1.11.40 contains the patch.
Executive priority
Treat this as an immediate remediation priority for affected, reachable systems. The combination of unauthenticated submission, low attack complexity, and potential administrator takeover creates substantial confidentiality and integrity risk. Confirm the estate, upgrade to 1.11.40, and investigate suspicious administrative activity.
Technical view
CVE-2026-39878 is stored cross-site scripting (CWE-79) in Chamilo LMS user registration. It is remotely reachable without authentication but requires an administrator to view the stored content. Execution occurs in the administrator’s browser context, crossing security scope and threatening confidentiality and integrity. CVSS 3.1 is 9.3 (critical).
Likely exposure
Internet-accessible Chamilo LMS deployments running version 1.11.38 or earlier are exposed, particularly where user registration is reachable. The supplied sources do not identify affected configurations beyond the registration form or establish whether registration must be enabled by default.
Exploitation context
The attack requires no authenticated account but does require administrator interaction with the stored registration data. Successful exploitation can produce full platform administrator takeover. The CVE is not identified as KEV, and the supplied bundle provides no evidence of active exploitation; this does not prove exploitation is absent.
Researcher notes
The supplied evidence establishes affected versions through 1.11.38 and a fix in 1.11.40, but does not explain the status of 1.11.39. It also provides no confirmed exploitation telemetry or specific indicators of compromise. Validation should remain authorized and non-destructive; consult the vendor advisory for implementation details.
Mitigation direction
- Upgrade affected Chamilo LMS installations to version 1.11.40.
- Review the GitHub security advisory for vendor-supported deployment guidance.
- Prioritize externally accessible systems and preserve relevant application and access logs.
- Review administrator accounts and security-sensitive changes for signs of unauthorized activity.
Validation and detection
- Inventory all Chamilo LMS instances and confirm their installed versions.
- Verify upgraded systems report Chamilo LMS version 1.11.40.
- Confirm public and internal registration endpoints are included in exposure assessments.
- Review recent registrations, administrator sessions, account changes, and configuration changes.
- Document that the supplied sources provide no specific indicators of compromise.
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-79: 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 lookupCVE-2026-39878 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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
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:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N2.85.8GitHub_MVulnerability scoring details
Base CVSS 3.1 score
9.3CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.
- 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/chamilo/chamilo-lms/security/advisories/GHSA-gcjp-f7jm-rrrgCVE reference, GitHub_M · x_refsource_CONFIRM
- https://vokecyber.com/research/cve-2026-39878-chamilo-lms-stored-xssCVE 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 Neutralization of Input During Web Page Generation
Improper Neutralization of Input During Web Page Generation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.