OpenSSL Release History & EOL Status

Understanding OpenSSL LTS and Support Lifecycle

OpenSSL is an open-source cryptographic library maintained by the OpenSSL Library project, with commercial support provided by the OpenSSL Corporation. Each release is classified as either LTS (Long Term Support) or non-LTS, and the support duration differs significantly between the two.

LTS releases are supported for at least five years from their initial release date. Non-LTS releases, starting from the 3.5 generation onwards, receive a minimum of 13 months of support. The project commits to designating a new LTS at least every two years, so there is always at least one actively supported LTS available.

In practice, most infrastructure teams pin to an LTS release and plan upgrades around the 5-year window. Non-LTS releases are better suited for projects that can afford frequent updates and want access to the latest API additions.

References: OpenSSL Roadmap, OpenSSL Versioning Policy, OpenSSL Corporation Support Plans.

What Are the Real Risks of Running an Unsupported OpenSSL Version?

Running an unsupported OpenSSL version means your TLS stack and cryptographic primitives no longer receive public security patches -- a direct exposure for anything that handles encrypted traffic, certificates, or key material.

OpenSSL vulnerabilities are not theoretical. High and critical severity CVEs affecting things like certificate verification, memory handling in handshake processing, and buffer overflows have historically targeted specific branches. Once a version reaches public EOL, those CVEs are disclosed but no patch is issued for that branch.

There are also forward-compatibility concerns. Newer TLS standards (TLS 1.3, post-quantum hybrid key exchange) and cipher suites are added only to supported branches. An unsupported version may negotiate weaker parameters or fail to connect to peers that enforce stricter policies.

For teams shipping software that bundles OpenSSL -- embedded systems, IoT firmware, language runtimes -- the risk compounds because the update path is not as simple as running a package upgrade. Knowing your EOL dates, as shown in the release table above, is the first step to staying ahead of this.

What Happens When an OpenSSL Version Reaches End of Support?

When an OpenSSL version reaches its End of OSS Support date, the project stops publishing security fixes for that branch publicly. The source code remains available, but any new vulnerabilities discovered will not be patched in that release.

For LTS versions specifically, two things diverge after the public EOL date: the open-source community support ends, but commercial extended support remains purchasable through the OpenSSL Corporation. This extended support has no fixed end date -- it continues as long as it remains commercially viable. Non-LTS versions do not have this option; they simply go dark.

Migration path

The general upgrade direction is to move to the current active LTS, as shown in the release table above. OpenSSL does not guarantee API or ABI compatibility across major version numbers, so a recompile (and sometimes code changes) is required when crossing a major boundary. The official OpenSSL Migration Guide covers the concrete API changes between major versions.

In practice, most teams have more migration work when jumping across a major version (e.g., 1.x to 3.x) than within the same major. Starting the upgrade assessment 6-12 months before EOL gives enough runway to handle dependency chains, especially if third-party libraries in your stack also link against OpenSSL.

How To Check Your OpenSSL Version

The fastest way to check which OpenSSL version is active on a system is to run the following command in your terminal:

openssl version

This prints the version string, for example OpenSSL 3.5.0 8 Apr 2025. To get the full build details including platform and compile-time options:

openssl version -a

If your application links OpenSSL dynamically, the system-level version and the runtime version may differ. You can verify what a running process is actually using with:

ldd /path/to/your/binary | grep ssl

For applications that embed OpenSSL statically or bundle their own copy (common in Go binaries, some Python wheels, or compiled appliances), check the vendor's release notes -- the system openssl command will not reflect what is linked inside the binary.

From within an application, the runtime version string is accessible via the OpenSSL_version() function (C API) or the equivalent in your language binding. Compare the version you find against the release table above to determine the End of OSS Support and premium support status.