CVE-2021-27764
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 · uneditedCookie without HTTPONLY flag set. NUMBER cookie(s) was set without Secure or HTTPOnly flags. The images show the cookie with the missing flag. (WebUI)
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 confidenceThe WebUI application sets cookies without the HttpOnly flag, allowing client-side JavaScript to access them. This enables session hijacking via XSS attacks. The Secure flag is also missing, meaning cookies can be transmitted over unencrypted HTTP connections.
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 dataall versionsCVSS 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
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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 if HCL BigFix WebUI is deployedCheck running processes or services for 'BigFix' or 'WebUI' components, or check if port 80/443 is serving BigFix WebUI applicationAffected if The application is running and serving BigFix WebUI requests
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Capture Set-Cookie response headersUse browser developer tools (Network tab), a proxy like Burp Suite, or curl -v to capture HTTP responses from the WebUI login and authenticated pages. Look for Set-Cookie headers in the responseAffected if Set-Cookie headers are present without HttpOnly and Secure flags
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Verify HttpOnly flag is missingInspect each Set-Cookie header and check if the 'HttpOnly' attribute is present. Example: Look for 'Set-Cookie: BFSession=...; HttpOnly' vs 'Set-Cookie: BFSession=...'Affected if Session cookies do NOT contain the HttpOnly attribute
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Verify Secure flag is missingInspect each Set-Cookie header and check if the 'Secure' attribute is present. Example: Look for 'Set-Cookie: BFSession=...; Secure' vs 'Set-Cookie: BFSession=...'Affected if Session cookies do NOT contain the Secure attribute, or are served over HTTP
If BigFix WebUI is running and its session cookies lack both HttpOnly and Secure flags in Set-Cookie headers, the environment is vulnerable to session hijacking via XSS and cookie exposure over unencrypted connections.
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 dataConfigure the application to set the HttpOnly and Secure flags on all session cookies. This is typically done in the cookie response header or application framework cookie configuration.
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27764 — 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-2021-27764 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
- No spam, self-promotion, credentials, or personal data