The regcomp function in the GNU C library version from 2.4 to 2.41 is subject to a double free if some previous allocation fails. It can be accomplished either by a malloc failure or by using an interposed malloc that injects random malloc failures. The double free can allow buffer manipulation depending of how the regex is constructed. This issue affects all architectures and ABIs supported by the GNU C library.
Exploitability
AV:LAC:HAT:PPR:LUI:PVulnerable System
VC:LVI:LVA:HSubsequent System
SC:LSI:LSA:H5.9/CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:H/SC:L/SI:L/SA:HOther