CVE-2018-8929
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 · uneditedImproper restriction of communication channel to intended endpoints vulnerability in HTTP daemon in Synology SSL VPN Client before 1.2.4-0224 allows remote attackers to conduct man-in-the-middle attacks via a crafted payload.
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 Synology SSL VPN Client contains an HTTP daemon with improper restriction of communication channels to intended endpoints. This vulnerability allows remote attackers to intercept and manipulate VPN traffic through man-in-the-middle attacks by sending crafted payloads, exploiting the lack of proper endpoint validation in the VPN client's HTTP communication layer.
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< 1.2.4-0224CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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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Verify if Synology SSL VPN Client is installedCheck installed programs or running processes for Synology SSL VPN Client - look for 'Synology SSL VPN Client' or 'sslvpnclient' in installed applications, services, or running processesAffected if The software is present on the system
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Locate the Synology SSL VPN Client executableSearch for sslvpnclient.exe or similar executable in common installation paths such as C:\Program Files\Synology\SSL VPN Client\ or check Program Files directoriesAffected if The executable exists in installation directories
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Determine installed version of Synology SSL VPN ClientRight-click the SSL VPN Client executable, select Properties, then look at the Version or Details tab to find the product version numberAffected if The displayed version number is lower than 1.2.4-0224
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Check VPN client configuration filesExamine configuration files in the Synology SSL VPN Client installation directory for version information or HTTP daemon settingsAffected if Configuration files indicate a version below 1.2.4-0224
The system is affected if Synology SSL VPN Client version 1.2.4-0224 or later is NOT installed, as versions prior to this contain the improper communication channel restriction vulnerability.
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 data1.2.4-0224
Update Synology SSL VPN Client to version 1.2.4-0224 or later to remediate the improper communication channel restriction vulnerability.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-8929 — 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-2018-8929 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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