CVE-2023-28807
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 · uneditedIn Zscaler Internet Access (ZIA) a mismatch between Connect Host and Client Hello's Server Name Indication (SNI) enables attackers to evade network security controls by hiding their communications within legitimate traffic.
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 confidenceIn Zscaler Internet Access, the Connect Host header is not validated against the Server Name Indication (SNI) in the TLS Client Hello. This mismatch allows attackers to send malicious traffic disguised as legitimate connections, bypassing ZIA security controls by presenting a valid SNI while the Connect Host points to a different destination.
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< 6.2r.290CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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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Check your ZIA versionLocate the Zscaler Internet Access version information in your admin console or system documentation. This is typically found under About, System Status, or Version Info sections in the ZIA portal.Affected if The installed version is lower than 6.2r.290 (e.g., 6.1r200, 6.0r150, etc.)
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Verify Connect Host to SNI validation policyIn your ZIA admin portal, navigate to the policy configuration section. Look for settings related to hostname validation, header inspection, or Connect proxy policies. Check whether there is a policy that validates the Connect Host header against the TLS SNI field.Affected if No policy exists or the policy is disabled that enforces matching between the Connect Host header and TLS SNI
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Confirm SNI inspection is enabledCheck your traffic inspection policies in ZIA. Look for SNI inspection, TLS inspection, or SSL inspection settings. Determine whether SNI inspection is actively processing traffic.Affected if SNI inspection is disabled or not configured for your policy scope
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Test for Connect Host and SNI mismatchIf you have access to logs or traffic analysis tools, examine TLS Client Hello messages passing through ZIA. Compare the SNI field in the Client Hello to the Connect Host header in the CONNECT request. Look for instances where these values differ.Affected if Traffic logs show CONNECT requests where the Connect Host does not match the SNI, and no policy is blocking these mismatches
You are affected if your ZIA version is below 6.2r.290 AND you do not have policies enforcing validation between Connect Host headers and TLS SNI, allowing mismatched connections to bypass security controls.
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.
dbcve · scoped6.2r.290
Configure ZIA to enforce strict hostname validation between the Connect Host header and TLS SNI, or enable SNI inspection policies to ensure traffic destination matches the declared SNI.
6.2r.290 or later
- Identify the current Zscaler Internet Access (ZIA) version in use
- Plan an upgrade window following Zscaler's standard upgrade procedures
- Upgrade ZIA to version 6.2r.290 or later
- After upgrade, verify that SNI validation is functioning correctly by confirming that Connect Host matches Client Hello SNI
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,728.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-28807 — 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-2023-28807 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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- Version or environment caveats, and links to real fixes
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