Aggregates CVE and security vulnerability intelligence across all stunnel-related products, including CVSS, EPSS, publication dates, and vulnerability intelligence data.
Historical issues mainly involve vendor risk buffer overflow, vendor risk memory corruption, and vendor risk denial of service and related problems; some flaws may lead to vendor impact application crash.
| CVE | Summary | Source | Max CVSS | EPSS % | Published | Updated |
|---|---|---|---|---|---|---|
| CVE-2021-20230 | A 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 certificate signed by a Certificate Authority, which is not the one accepted by the stunnel server, to access the tunneled service instead of being redirected to the address specified in the redirect option. The highest threat from this vulnerability is to confidentiality. | [email protected] | 7.5 | 0.20% | 2021-02-23 | 2024-11-21 |
| CVE-2015-3644 | Stunnel 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 authentication. | [email protected] | 5.8 | 0.16% | 2015-05-14 | 2026-05-06 |
| CVE-2014-0016 | stunnel 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 use the same entropy pool and allows remote attackers to obtain private keys for EC (ECDSA) or DSA certificates. | [email protected] | 4.3 | 0.31% | 2014-03-24 | 2026-05-06 |
| CVE-2013-1762 | 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. | [email protected] | 6.6 | 2.01% | 2013-03-08 | 2026-04-29 |
| CVE-2011-2940 | stunnel 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. | [email protected] | 9.3 | 15.84% | 2011-08-25 | 2026-04-29 |
| CVE-2008-2420 | The 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 certificates. | [email protected] | 6.8 | 0.49% | 2008-05-23 | 2026-04-23 |
| CVE-2008-2400 | Unspecified vulnerability in stunnel before 4.23, when running as a service on Windows, allows local users to gain privileges via unknown attack vectors. | [email protected] | 7.2 | 0.05% | 2008-05-22 | 2026-04-23 |
| CVE-2003-0740 | Stunnel 4.00, and 3.24 and earlier, leaks a privileged file descriptor returned by listen(), which allows local users to hijack the Stunnel server. | [email protected] | 4.6 | 0.12% | 2003-10-20 | 2026-04-16 |
| CVE-2002-1563 | stunnel 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. | [email protected] | 1.2 | 0.06% | 2003-05-12 | 2026-04-16 |
| CVE-2003-0147 | OpenSSL 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 reductions during Montgomery reduction, and (2) the use of different integer multiplication algorithms ("Karatsuba" and normal). | [email protected] | 5.0 | 28.74% | 2003-03-31 | 2026-04-16 |
| CVE-2002-0002 | Format 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. | [email protected] | 7.5 | 15.62% | 2002-01-31 | 2026-04-16 |
| CVE-2001-0060 | Format string vulnerability in stunnel 3.8 and earlier allows attackers to execute arbitrary commands via a malformed ident username. | [email protected] | 10.0 | 1.06% | 2001-02-12 | 2026-04-16 |