Stunnel

This hub aggregates every CVE we track for Stunnel, a product in the security products space. Use it to gauge the current risk picture and drill into individual advisories.

Severity distribution

Monthly trend

The 14 most recently published vulnerabilities affecting Stunnel.

• CVE-2026-70368Stunnel: stack-based out-of-bounds read/write in stunnel s_vlog via oversized log message6.5Aug 4, 2026
• CVE-2026-70367Stunnel: ssrf bypass in stunnel socks proxy via ipv4-mapped ipv6 loopback and unspecified addresses allows access to loopback-only services5.4Aug 4, 2026
• CVE-2021-20230A flaw was found in stunnel before 5.57, where it improperly validates client certificates when it is configured to use both redirect and verifyChain options. This flaw allows an attacker with a ce...7.5Feb 23, 2021
• CVE-2015-3644Stunnel 5.00 through 5.13, when using the redirect option, does not redirect client connections to the expected server after the initial connection, which allows remote attackers to bypass authenti...5.8May 14, 2015
• CVE-2014-0016stunnel before 5.00, when using fork threading, does not properly update the state of the OpenSSL pseudo-random number generator (PRNG), which causes subsequent children with the same process ID to...4.3Mar 23, 2014
• CVE-2013-1762stunnel 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 arbitra...6.6Mar 8, 2013
• CVE-2011-2940stunnel 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.9.3Aug 25, 2011
• CVE-2008-2420The OCSP functionality in stunnel before 4.24 does not properly search certificate revocation lists (CRL), which allows remote attackers to bypass intended access restrictions by using revoked cert...6.8May 23, 2008
• CVE-2008-2400Unspecified vulnerability in stunnel before 4.23, when running as a service on Windows, allows local users to gain privileges via unknown attack vectors.7.2May 22, 2008
• CVE-2003-0740Stunnel 4.00, and 3.24 and earlier, leaks a privileged file descriptor returned by listen(), which allows local users to hijack the Stunnel server.4.6Sep 4, 2003
• CVE-2002-1563stunnel 4.0.3 and earlier allows attackers to cause a denial of service (crash) via SIGCHLD signal handler race conditions that cause an inconsistency in the child counter.1.2Apr 26, 2003
• CVE-2003-0147OpenSSL does not use RSA blinding by default, which allows local and remote attackers to obtain the server's private key by determining factors using timing differences on (1) the number of extra r...5.0Mar 18, 2003
• CVE-2002-0002Format string vulnerability in stunnel before 3.22 when used in client mode for (1) smtp, (2) pop, or (3) nntp allows remote malicious servers to execute arbitrary code.7.5Jun 25, 2002
• CVE-2001-0060Format string vulnerability in stunnel 3.8 and earlier allows attackers to execute arbitrary commands via a malformed ident username.10.0May 7, 2001