CVE-2013-1762: stunnel 4.21 through 4.54, when CONNECT protocol negotiation and NTLM authentication are enabled, does not cor

Q: How do I fix CVE-2013-1762?

stunnel: upgrade to newer than 4.54. Exact commands for each OS are on this page.

Q: Is CVE-2013-1762 being exploited?

CVE-2013-1762 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2013-1762 affect?

CVE-2013-1762 affects stunnel. Severity is medium (CVSS 6.6). 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

Q: How urgent is CVE-2013-1762?

Priority 45/100. No elevated risk signals yet.

This month

MEDIUM 6.6UPGRADE

CVE-2013-1762 is a medium-severity flaw (CVSS 6.6) affecting stunnel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.6 (Medium)
EPSS exploit chance	2.9% (top 13%)
CISA exploited list	No
Weakness	CWE-94
Published	2013-03-08
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: stunnel

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2013-03-08 18:55 UTCPublished CVE record published
2026-06-16 23:52 UTCUpdated Record last modified

stunnel stunnel UPGRADE

Affected: <= 4.54 · 4.21 · 4.22 · 4.23 · 4.24 · 4.25 · 4.26 · 4.27

Fixed in: newer than 4.54

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy stunnel || rpm -q stunnel || stunnel --version

2. UPGRADE to newer than 4.54 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade stunnel

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade stunnel

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2013-1762?

stunnel: upgrade to newer than 4.54. Exact commands for each OS are on this page.

Is CVE-2013-1762 being exploited?

CVE-2013-1762 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2013-1762 affect?

CVE-2013-1762 affects stunnel. Severity is medium (CVSS 6.6). 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

How urgent is CVE-2013-1762?

Priority 45/100. No elevated risk signals yet.

Related CVEs

CVE-2021-20230 HIGH 7.5 UPGRADE A flaw was found in stunnel before 5.57, where it improperly validates client certificates when it is configur
CVE-2015-3644 MEDIUM 5.8 DOWNGRADE Stunnel 5.00 through 5.13, when using the redirect option, does not redirect client connections to the expecte
CVE-2014-0016 MEDIUM 4.3 UPGRADE stunnel before 5.00, when using fork threading, does not properly update the state of the OpenSSL pseudo-rando
CVE-2011-2940 HIGH 9.3 DOWNGRADE stunnel 4.40 and 4.41 might allow remote attackers to execute arbitrary code or cause a denial of service (hea

References

← Back to latest CVEs