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StunnelApplication

CVE-2013-1762

MEDIUM · 6.6 CVSS v2.0 Published 2013-03-08
Fix available
A fix is available. Upgrade to after 4.54 or later.
See remediation →
75/100
Remediation priority · High
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
stunnel 4.21 through 4.54, when CONNECT protocol negotiation and NTLM authentication are enabled, does not correctly perform integer conversion, which allows remote proxy servers to execute arbitrary code via a crafted request that triggers a buffer overflow.

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

stunnel versions 4.21 through 4.54 contain a buffer overflow vulnerability triggered by improper integer conversion when both CONNECT protocol negotiation and NTLM authentication are enabled simultaneously, allowing remote proxy servers to execute arbitrary code via crafted requests.

MitigationUpgrade stunnel to version 4.55 or later to patch the integer conversion flaw; alternatively, if NTLM authentication is not required, disable it to eliminate the attack vector.

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
StunnelApplication
Affected:<= 4.54= 4.21= 4.22= 4.23= 4.24= 4.25= 4.26= 4.27= 4.28= 4.29= 4.30= 4.31

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
High
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Complete

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

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

  1. Determine stunnel version
    Run 'stunnel -version' or 'stunnel -help' to display the version information
    Affected if The version displayed is between 4.21 and 4.54 inclusive
  2. Locate stunnel configuration file
    Check common configuration paths such as /etc/stunnel/stunnel.conf, /etc/stunnel.conf, or the path specified via the '-d' option when starting stunnel
    Affected if A configuration file exists and is in use
  3. Check if CONNECT protocol is enabled
    Examine the configuration file for 'protocol = CONNECT' or similar CONNECT protocol settings in the service sections
    Affected if CONNECT protocol is explicitly enabled in the configuration
  4. Check if NTLM authentication is enabled
    Examine the configuration file for 'NTLMauth = yes' or 'auth = NTLM' directives within service definitions
    Affected if NTLM authentication is explicitly enabled in any service section

You are affected if stunnel version is 4.21 through 4.54 AND both CONNECT protocol and NTLM authentication are simultaneously enabled in your configuration

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
Upgrade available Upgrade to a release after 4.54
Interim mitigation

Upgrade stunnel to version 4.55 or later to patch the integer conversion flaw; alternatively, if NTLM authentication is not required, disable it to eliminate the attack vector.

Fix this in Stunnel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

Scan for this in your stack

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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-2013-1762 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