Security readout for executives and security teams
Plain-English summary
ExponentCMS 2.6 and earlier may trust a modified HTTP Host header when building page links. An attacker could make links on the site point to an arbitrary host, creating phishing or man-in-the-middle risk. The sources do not provide CVSS, confirmed exploitation, or a named fixed version.
Executive priority
Treat this as a moderate web application hygiene issue unless ExponentCMS is internet-facing and customer-facing. Prioritize inventory, hostname hardening, and vendor guidance review over emergency response, because active exploitation and CVSS are not evidenced here.
Technical view
CVE-2021-38751 describes an HTTP Host header issue in /exponent_constants.php. By altering the Host header, generated webpage links can be changed to an arbitrary value. The source bundle identifies ExponentCMS 2.6 and below, but provides limited remediation detail and no exploit-in-the-wild evidence.
Likely exposure
Primary exposure is public or internal websites running ExponentCMS 2.6 or earlier. Exposure depends on whether the application or upstream proxy accepts untrusted Host headers and uses them when generating absolute links.
Exploitation context
The CVE is not listed as KEV, and the provided sources do not claim active exploitation. The described impact is link manipulation that could support phishing, traffic redirection, or man-in-the-middle scenarios if users trust generated links.
Researcher notes
Evidence is sparse: the CVE description and referenced GitHub issue identify the affected path and behavior, but not a CVSS vector, CWE, patch level, or exploitation status. Avoid asserting specific fixes beyond vendor guidance and trusted-host hardening.
Mitigation direction
- Check ExponentCMS vendor or project guidance for a fixed release or configuration advice.
- Inventory and upgrade ExponentCMS 2.6 or earlier where supported guidance exists.
- Reject untrusted Host headers at the reverse proxy or web server.
- Configure a canonical hostname for the site where the platform supports it.
Validation and detection
- Confirm whether any deployed site runs ExponentCMS 2.6 or earlier.
- Review web server and proxy rules for accepted hostnames.
- Inspect application configuration for canonical URL or trusted host settings.
- Check generated absolute links for dependence on request Host values.
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-2021-38751 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://github.com/exponentcms/exponent-cms/issues/1544CVE 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.