Security readout for executives and security teams
Plain-English summary
Older Invision Community/IP-Board sites could expose users to script injection because uploaded filenames may be guessed. A successful attack could affect user sessions or site trust, depending on privileges and configuration. The bundle does not show confirmed exploitation, but public disclosure and vendor release notes make upgrade verification important.
Executive priority
Prioritize remediation for public forums or customer communities running affected versions. The business risk is user compromise and reputational damage, with possible higher impact if the advisory chain applies. No active exploitation is evidenced in the provided bundle.
Technical view
CVE-2021-39249 affects Invision Community before 4.6.5.1. The CVE describes reflected XSS caused by predictable uploaded-file filenames after brute forcing PHP mt_rand output. The SSD advisory title indicates a broader stored-XSS-to-RCE chain, but this bundle does not provide enough detail to independently characterize the full chain.
Likely exposure
Exposure is most likely on internet-facing Invision Community, IPS Community Suite, or IP-Board installations older than 4.6.5.1, especially where file upload functionality is available to users.
Exploitation context
CISA KEV status is false in the bundle, and no cited source here confirms active exploitation. The issue is publicly disclosed, and the linked advisory discusses a more serious chain, so defenders should treat public-facing legacy deployments as higher priority.
Researcher notes
Evidence is limited to the CVE description, SSD advisory link, and Invision 4.6.5.1 release notes. Treat the reflected XSS mechanism as sourced; treat any RCE implications cautiously unless confirmed by the full advisory or vendor documentation.
Mitigation direction
- Upgrade Invision Community/IP-Board to 4.6.5.1 or later.
- Review Invision release notes and vendor guidance for related security fixes.
- Inventory public community sites and confirm exact installed versions.
- Limit untrusted upload capability where business operations allow.
- Increase monitoring for suspicious upload and script-injection activity.
Validation and detection
- Check whether any deployment runs Invision Community before 4.6.5.1.
- Confirm exposed sites allow user-controlled file uploads.
- Review web logs for unusual upload filename probing patterns.
- Verify the vendor security update is installed in production.
- Confirm no unreviewed customizations bypass upload handling controls.
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.
CVE-2021-39249 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://ssd-disclosure.com/ssd-advisory-ip-board-stored-xss-to-rce-chain/CVE reference · x_refsource_MISC
- https://invisioncommunity.com/release-notes/4651-r102/CVE reference · 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.