CVE-2026-21826
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedHCL Digital Experience and HCL Digital Experience Compose could be susceptible to Host header injection. An attacker can manipulate the Host header and cause the application to behave in unexpected ways.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThis is a Host Header Injection vulnerability in HCL Digital Experience. The application trusts and uses the Host header value from HTTP requests without proper validation, allowing attackers to manipulate it and cause unexpected behavior such as malicious redirects, link poisoning, or cache poisoning.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 9.5= 9.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify HCL Digital Experience product and versionCheck the installed version of HCL Digital Experience or HCL Digital Experience Compose. This is typically found in the product installation directory, version.info file, or via the Digital Experience Administration Console under 'Version Information'. Compare your version to the affected range: version 9.5Affected if The installed product version is exactly 9.5 for either HCL Digital Experience Compose or HCL Digital Experience
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Verify Host header handling in web server configurationInspect the web server configuration (e.g., IHS plugin-config.xml, httpd.conf, or reverse proxy config) for how the Host header is processed. Look for directives that may trust or use the Host header value without validationAffected if The configuration allows the Host header to be used directly in URL generation without validation against an allowlist
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Test for Host header injection in redirectsSend an HTTP request with a manipulated Host header (e.g., Host: attacker.com) to the Digital Experience server and observe if redirects or generated URLs reflect the injected Host value instead of the legitimate server nameAffected if Redirect responses or generated URLs contain the attacker-controlled Host header value rather than the legitimate server domain
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Check application URL generation behaviorExamine HTTP response headers and body content, particularly for password reset links, cacheable resources, or redirect locations. Compare the URLs generated against the actual server nameAffected if Generated absolute URLs, password reset tokens, or cached resources use a Host header value that differs from the legitimate server
A user is affected if they are running HCL Digital Experience or HCL Digital Experience Compose version 9.5 and the application uses the Host header to construct URLs without validation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataValidate the Host header against an explicit allowlist of permitted values and avoid using it in generated URLs, redirects, or password reset links without sanitization. Configure the web server to reject requests with unexpected Host headers.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21826 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-21826 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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