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Home / Blog / openssl 1.0.2
Security Advisory

OpenSSL 1.0.2: 98 CVEs Found in 5,210 Websites

📅 June 07, 2026 ·⏱ 5 min read ·🔒 SiteRecipe Security Team
5,210 websites still running openssl 1.0.2  → View full list
98
Total
7
Critical
26
High
59
Medium
6
Low

OpenSSL 1.0.2 is an outdated cryptographic library that powers the SSL/TLS encryption on thousands of websites worldwide. Despite being end-of-life since December 2019, over 5,210 websites still rely on this vulnerable version. Our security research has identified 98 known vulnerabilities, including 7 critical-severity flaws that could allow attackers to execute arbitrary code, steal data, or crash your website entirely.

If your website is running OpenSSL 1.0.2, you're at significant risk. Cybercriminals actively exploit these known vulnerabilities to breach websites and steal sensitive information from visitors. The longer you wait to upgrade, the more exposed your site becomes to sophisticated attacks targeting these specific weaknesses.

This comprehensive guide will show you how to identify if your website uses vulnerable OpenSSL 1.0.2, understand the specific threats you face, and implement a safe upgrade path to protect your users and business.

What is Openssl 1.0.2?

OpenSSL is the cryptographic library that secures internet communications. It's the technology behind HTTPS—the padlock icon in your browser's address bar. When you visit a website, OpenSSL encrypts the data traveling between your computer and the web server, preventing hackers from intercepting passwords, credit card numbers, or personal information. Without OpenSSL, modern internet security would be impossible.

OpenSSL 1.0.2 was released in January 2015 and served as a stable version for many years. However, technology constantly evolves, and security vulnerabilities are regularly discovered in older software. OpenSSL 1.0.2 reached end-of-life in December 2019, meaning the developers stopped releasing security patches. This means any new vulnerabilities discovered after that date will never be fixed. Running outdated OpenSSL is like leaving your front door unlocked—attackers know exactly where to find the vulnerabilities and how to exploit them.

Key Vulnerabilities in Openssl 1.0.2

98 CVEs found. The most critical are explained below.

CRITICAL CVE-2016-0705 9.8/10 · CVSS v3.0 ⏱ Immediate
Double Free Memory Vulnerability in DSA Encryption

OpenSSL has a bug where it tries to free the same memory twice when processing certain encryption keys. This happens automatically when your server handles these malformed keys. Attackers can exploit this by sending specially crafted encryption keys to your server.

Impact: Your website could crash or become unstable. In worst cases, attackers might gain control of your server or access sensitive data.

↗ View on NVD
CRITICAL CVE-2016-0799 9.8/10 · CVSS v3.0 ⏱ Immediate
String Length Calculation Error in OpenSSL

OpenSSL miscalculates how long certain text strings are when processing data. When very long strings are sent to your server, this calculation fails. Attackers can send oversized strings to trigger the vulnerability.

Impact: Your server could crash or become unstable. Attackers might read sensitive information from your server's memory.

↗ View on NVD
CRITICAL CVE-2016-2842 9.8/10 · CVSS v3.0 ⏱ Immediate
Memory Allocation Failure in Data Processing

OpenSSL doesn't properly check if it successfully allocated memory when processing certain data. If memory allocation fails silently, the software writes data to wrong memory locations. Remote attackers can trigger this condition.

Impact: Your server could crash, consume excessive memory, or be compromised. Data could be corrupted or stolen.

↗ View on NVD
CRITICAL CVE-2016-2108 9.8/10 · CVSS v3.0 ⏱ Immediate
ASN.1 Negative Zero Buffer Underflow

OpenSSL has a flaw in how it reads certain encrypted data formats (ASN.1). A crafted data input can cause the software to write data before allocated memory boundaries. This is a sophisticated but critical vulnerability.

Impact: Attackers could execute malicious code on your server, crash it, or access confidential information like encryption keys and customer data.

↗ View on NVD
CRITICAL CVE-2016-2177 9.8/10 · CVSS v3.0 ⏱ Immediate
Pointer Arithmetic Integer Overflow in Memory Checks

OpenSSL uses incorrect math when checking memory boundaries for data processing. This mathematical error can be bypassed by attackers sending specific data patterns. The vulnerability relates to how the server handles incoming encrypted connections.

Impact: Your server could crash. Attackers might bypass security checks and access unencrypted data or execute malicious code.

↗ View on NVD
CRITICAL CVE-2025-34192 9.8/10 · CVSS v3.1 ⏱ Immediate
End-of-Life OpenSSL in PrinterLogic Virtual Appliance

Vasion Print Virtual Appliance and older macOS/Linux clients use OpenSSL 1.0.2h from May 2016, which stopped receiving security updates in 2019. These versions contain all the critical vulnerabilities listed above. Your organization is running software that no longer receives protection.

Impact: All the vulnerabilities above apply to your system simultaneously with no vendor support. Your printing infrastructure is highly vulnerable to attacks and data breaches.

↗ View on NVD

Additional Vulnerabilities (92 more)

Showing first 10 of 92. View all on NVD ↗

CVE IDSeverityScore PublishedDescription
CVE-2020-7043 CRITICAL 9.1 2020-02-27 An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL before 1.0.2. tunnel.c mishandles certificate validation because hostname comparisons do not consider '\0' ch…
CVE-2025-15467 HIGH 8.8 2026-01-27 Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with maliciously crafted AEAD parameters can trigger a stack buffer overflow. Impact summary: A stack buffer…
CVE-2016-2176 HIGH 8.2 2016-05-05 The X509_NAME_oneline function in crypto/x509/x509_obj.c in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h allows remote attackers to obtain sensitive information from process stac…
CVE-2019-12572 HIGH 7.8 2019-06-21 A vulnerability in the London Trust Media Private Internet Access (PIA) VPN Client 1.0.2 (build 02363) for Windows could allow an authenticated, local attacker to run arbitrary co…
CVE-2015-1789 HIGH 7.5 2015-06-12 The X509_cmp_time function in crypto/x509/x509_vfy.c in OpenSSL before 0.9.8zg, 1.0.0 before 1.0.0s, 1.0.1 before 1.0.1n, and 1.0.2 before 1.0.2b allows remote attackers to cause …
CVE-2015-3193 HIGH 7.5 2015-12-06 The Montgomery squaring implementation in crypto/bn/asm/x86_64-mont5.pl in OpenSSL 1.0.2 before 1.0.2e on the x86_64 platform, as used by the BN_mod_exp function, mishandles carry…
CVE-2015-3194 HIGH 7.5 2015-12-06 crypto/rsa/rsa_ameth.c in OpenSSL 1.0.1 before 1.0.1q and 1.0.2 before 1.0.2e allows remote attackers to cause a denial of service (NULL pointer dereference and application crash)…
CVE-2016-0797 HIGH 7.5 2016-03-03 Multiple integer overflows in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g allow remote attackers to cause a denial of service (heap memory corruption or NULL pointer deref…
CVE-2016-0798 HIGH 7.5 2016-03-03 Memory leak in the SRP_VBASE_get_by_user implementation in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g allows remote attackers to cause a denial of service (memory consump…
CVE-2016-2105 HIGH 7.5 2016-05-05 Integer overflow in the EVP_EncodeUpdate function in crypto/evp/encode.c in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h allows remote attackers to cause a denial of service (hea…
Full Report Available

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How to Fix These Vulnerabilities

Conclusion

OpenSSL 1.0.2's 98 vulnerabilities represent a serious security risk that extends beyond your website to your visitors' data and privacy. The 7 critical-severity flaws documented in this article could allow attackers to execute code on your server, crash your site, or steal encryption keys. With over 5,210 websites still running this outdated version, attackers have plenty of targets—don't let yours be one of them.

Upgrading OpenSSL is one of the most important security investments you can make today. SiteRecipe.com makes this process simple with our comprehensive vulnerability scanning and remediation guidance. Visit SiteRecipe.com now to scan your website for vulnerable OpenSSL versions, get personalized upgrade recommendations, and join thousands of websites protecting their users from these critical threats. Your website security—and your users' trust—depends on it.

Frequently Asked Questions

How critical are the vulnerabilities in OpenSSL 1.0.2?
Very critical. The 7 critical-severity CVEs in OpenSSL 1.0.2 can allow remote attackers to execute arbitrary code on your server without authentication, cause denial-of-service attacks that crash your site, or corrupt memory in ways that compromise your entire system. These aren't theoretical vulnerabilities—they're actively exploited by real-world attackers.
Will upgrading OpenSSL break my website?
Upgrading OpenSSL rarely breaks websites when done properly. Most modern hosting environments and applications are compatible with OpenSSL 1.1.1+. The key is backing up your site first and testing thoroughly afterward. SiteRecipe.com provides step-by-step guidance to minimize disruption.
Why are 5,210 websites still using OpenSSL 1.0.2 if it's so dangerous?
Many website owners are unaware their site uses outdated OpenSSL, or they fear the upgrade process will cause problems. Legacy websites built years ago sometimes require special configuration changes to upgrade safely. SiteRecipe.com's scanner helps you identify if you're at risk and provides clear upgrade paths tailored to your specific setup.
Can attackers exploit these vulnerabilities remotely?
Yes, several critical CVEs in OpenSSL 1.0.2 can be exploited remotely without requiring server access. This means attackers anywhere on the internet can potentially compromise your site. This is why upgrading immediately is crucial—every day you delay is another day your site is exposed.
How long does it take to upgrade from OpenSSL 1.0.2?
For most websites, the upgrade takes 30 minutes to 2 hours from start to finish, including backup, upgrade, testing, and verification. Complex setups with custom applications may take longer. SiteRecipe.com provides timeline estimates based on your specific infrastructure.

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DISCLAIMER: This report is based on publicly available CVE data from the National Vulnerability Database (NVD) maintained by NIST. Detection of a technology version does not confirm active exploitation on any specific website. For informational purposes only. SiteRecipe is not responsible for actions taken based on this report. Always consult a qualified security professional.

Source: nvd.nist.gov · Published: June 07, 2026 · SiteRecipe.com