Yes
Most weak-copyleft licenses (including GNU Lesser GPL v2.1) are designed to combine with GPL-family ones. Verify the specific weak-copyleft license version against GNU GPL v2.0 or later's compatibility list (FSF maintains an authoritative one).
| License | Family | Patent grant |
|---|---|---|
| GNU Lesser GPL v2.1 (LGPL-2.1) | weak-copyleft | No (implicit at most) |
| GNU GPL v2.0 or later (GPL-2.0-or-later) | strong-copyleft | No (implicit at most) |
GNU Lesser GPL v2.1: Library copyleft: dynamic linking permitted from non-LGPL code without triggering full copyleft.
GNU GPL v2.0 or later: GPL-2.0 with explicit upgrade path; users may pick GPL-2.0 or any later GPL.
If you found this page because you're trying to figure out whether shipping a particular dependency is safe, the answer above is a starting point — not a substitute for reading the actual licenses or talking to a lawyer when stakes are high.
LicenseHound walks every transitive dependency in your repo, maps each to its SPDX license, and flags pairs like this one in PR comments. The CLI is free; the team dashboard is paid.