Gnu · Gnu Bison · CVE-2020-24240
**Name of the Vulnerable Software and Affected Versions**
GNU Bison versions prior to 3.7.1
**Description**
The issue arises from a use-after-free in ` obstack free` in `lib/obstack.c`, which is called from `gram lex`, when a '0' byte is encountered. This poses a risk only if GNU Bison is used with untrusted input, and the observed bug causes unsafe behavior with a specific compiler or architecture. The bug report indicates that a crash may occur in GNU Bison itself.
**Recommendations**
For GNU Bison versions prior to 3.7.1, update to version 3.7.1 or later to resolve the issue. As a temporary workaround, consider avoiding the use of GNU Bison with untrusted input until a patch is available.