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TigervncApplication

CVE-2011-1775

MEDIUM · 5.8 CVSS v2.0 Published 2011-05-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
The CSecurityTLS::processMsg function in common/rfb/CSecurityTLS.cxx in the vncviewer component in TigerVNC 1.1beta1 does not properly verify the server's X.509 certificate, which allows man-in-the-middle attackers to spoof a TLS VNC server via an arbitrary certificate.

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 · high confidence

The CSecurityTLS::processMsg function in TigerVNC's vncviewer component fails to properly validate the server's X.509 certificate during TLS handshake, allowing man-in-the-middle attackers to impersonate a VNC server using an arbitrary certificate.

MitigationUpgrade to TigerVNC version 1.1 or later where proper certificate verification is implemented; alternatively, manually verify server certificates out-of-band before trusting 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 data
TigervncApplication
Affected:= 1.1

CVSS 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
M
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
None

AV:N/AC:M/Au:N/C:P/I:P/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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm TigerVNC vncviewer is installed
    Run 'vncviewer -version' or check package manager for tigervnc package
    Affected if No TigerVNC vncviewer installed means not affected
  2. Identify the installed TigerVNC version
    Run 'vncviewer -version' and note the version number
    Affected if Version is exactly 1.1 (the vulnerable version)
  3. Verify TLS/SSL encryption is enabled for VNC connections
    Check if VNC connection is configured to use TLS or SSL (look for 'TLS' or 'SecurityTypes' in vncviewer config or connection parameters)
    Affected if TLS encryption is NOT enabled - the flaw only applies when TLS handshake occurs
  4. Check for custom certificate verification
    Inspect any user-provided certificate trust configuration or script used alongside vncviewer connections
    Affected if No custom certificate validation is in place - the vulnerability exists exactly when relying on built-in TLS validation

User is affected only if running TigerVNC vncviewer version 1.1 with TLS encryption enabled and relying on the built-in certificate validation without manual out-of-band verification.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to TigerVNC version 1.1 or later where proper certificate verification is implemented; alternatively, manually verify server certificates out-of-band before trusting connections.

Fix this in Tigervnc Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,790
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-1775 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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