GPLv2, the GNU General Public License version 2, is a copyleft open-source license. It lets anyone use, modify, and redistribute the covered code, but if you distribute a derivative work, you must provide the corresponding source code and preserve the same license terms.
In cyber security, GPLv2 matters because many security tools and libraries are reused in downstream products. If a vendor rebuilds or embeds GPLv2 code, defenders can use the license to reason about source availability, version lineage, and whether patches should be visible in the distributed binary. Attackers and shady vendors sometimes try to obscure provenance by wrapping GPLv2 software in a new brand, but the license obligations still apply. For defenders, checking the source offer, build metadata, and upstream references helps confirm whether a product is a clean rebuild, a modified fork, or a compliance risk.