CVE-2011-2940
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 · uneditedstunnel 4.40 and 4.41 might allow remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.
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 confidenceHeap memory corruption vulnerability in stunnel versions 4.40 and 4.41 allows remote attackers to execute arbitrary code or cause denial of service via unspecified vectors. The vulnerability has a CVSS score of 9.3 indicating critical severity.
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= 4.40= 4.41CVSS 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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:M/Au:N/C:C/I:C/A:C
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.
-
Check if stunnel is installedRun 'which stunnel' or 'stunnel -version' to locate the stunnel binaryAffected if If stunnel command is not found, the system is not affected by this specific vulnerability
-
Determine installed stunnel versionRun 'stunnel -version 2>&1' or 'stunnel -version' to display version informationAffected if The output shows version 4.40 or 4.41 exactly - these are the vulnerable versions
-
Verify version via package managerOn Debian/Ubuntu run 'dpkg -l | grep -i stunnel'; on RHEL/CentOS run 'rpm -qa | grep -i stunnel'Affected if Package version listed as stunnel-4.40 or stunnel-4.41 confirms the vulnerable version is installed
-
Check stunnel configuration filesInspect configuration files in common locations such as /etc/stunnel/stunnel.conf or /etc/stunnel.confAffected if Configuration presence alone does not indicate vulnerability - version check in step 2 is definitive
A system is affected only if the installed stunnel version is exactly 4.40 or exactly 4.41; any other version (including 4.42 and later) is not vulnerable to this specific CVE.
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 · scopedUpgrade stunnel to a version beyond 4.41 ( patched versions are available). Given the critical severity and RCE potential, consider implementing network-level access controls as an interim measure while patching is scheduled.
Stunnel 4.42 or later stable release
- 1. Identify all systems running Stunnel versions 4.40 or 4.41
- 2. Download the fixed Stunnel release from the official source at stunnel.org
- 3. Before upgrading, backup the current stunnel configuration files (typically stunnel.conf)
- 4. Stop the stunnel service on each affected system
- 5. Install the upgraded stunnel package or compile from source
- 6. Verify the stunnel service starts successfully with the new version
- 7. Test that the stunnel service is properly accepting connections and forwarding traffic
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 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 $3,392.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-2940 — 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-2011-2940 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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