It appears to be a custom licence, which, as stated on the page, is inspired by the MIT/X11 licence. The only difference from MIT/X11 appears to be the the part

It appears to be a custom licence, which, as stated on the page, is inspired by the MIT/X11 licence. The only difference from MIT/X11 appears to be the the part before the warranty disclaimer, which has been shortened. SPDX has a separate entry for it [1]. [1] https://spdx.org/licenses/curl.html https://spdx.org/licenses/curl.html