Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 13.93% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2021-31933High confidence
n/a — Use of Incorrectly-Resolved Name or Reference
Unknown · Unknown
7.2HighCVSS 3.1
Within 7 days
Patch availableHigh technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 3 Aug 2024
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
A remote code execution vulnerability exists in Chamilo through 1.11.14 due to improper input sanitization of a parameter used for file uploads, and improper file-extension filtering for certain filenames (e.g., .phar or .pht). A remote authenticated administrator is able to upload a file containing arbitrary PHP code into specific directories via main/inc/lib/fileUpload.lib.php directory traversal to achieve PHP code execution.
What
A remote code execution vulnerability exists in Chamilo through 1.11.14 due to improper input sanitization of a parameter used for file uploads, and improper file-extension filtering for certain filenames (e.g., .phar or .pht). A remote authenticated administrator is able to upload a file containing arbitrary PHP code into specific directories via main/inc/lib/fileUpload.lib.php directory traversal to achieve PHP code execution.
Why
The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere.
How
An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.
What
A remote code execution vulnerability exists in Chamilo through 1.11.14 due to improper input sanitization of a parameter used for file uploads, and improper file-extension filtering for certain filenames (e.g., .phar or .pht). A remote authenticated administrator is able to upload a file containing arbitrary PHP code into specific directories via main/inc/lib/fileUpload.lib.php directory traversal to achieve PHP code execution.
Why
The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere.
How
An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- a network path → Use of Incorrectly-Resolved Name or Reference → execute code or commands in the affected security context
- Attack surface
- Network
- Privileges required
- High: elevated access is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-706 ↗
CWE-706: Use of Incorrectly-Resolved Name or Reference. The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AC:L/AV:N/A:H/C:H/I:H/PR:H/S:U/UI:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.AVNetworkAttack vector: The vulnerable component can be reached over a network.AHighAvailability impact: A successful attack can cause a major loss.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.PRHighPrivileges required: The attacker needs elevated or administrative privileges.SUnchangedScope: The security impact remains within the vulnerable component's authority.UINoneUser interaction: No action by another user is required.- Post-exploitation / living off the land
- After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- n/a
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 30 Apr 2021 · Last source change 3 Aug 2024, 23:10 UTC · CWE-706 · Use of Incorrectly-Resolved Name or Reference
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-18806
Product sourceUnavailable
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.