{"id":"UBUNTU-CVE-2020-24240","details":"GNU Bison before 3.7.1 has a use-after-free in _obstack_free in lib/obstack.c (called from gram_lex) when a '\\0' byte is encountered. NOTE: there is a risk only if Bison is used with untrusted input, and the observed bug happens to cause unsafe behavior with a specific compiler/architecture. The bug report was intended to show that a crash may occur in Bison itself, not that a crash may occur in code that is generated by Bison.","modified":"2026-09-21T10:00:30.828542145Z","published":"2020-08-25T14:15:00Z","upstream":["CVE-2020-24240"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-24240"},{"type":"REPORT","url":"https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-24240"}],"affected":[{"package":{"name":"bison","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/bison?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:3.0.2.dfsg-2","2:3.0.4.dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_version":"2:3.0.4.dfsg-1","binary_name":"bison"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-24240.json"}},{"package":{"name":"bison","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/bison?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:3.0.4.dfsg-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"bison","binary_version":"2:3.0.4.dfsg-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-24240.json"}},{"package":{"name":"bison","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/bison?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:3.4.1+dfsg-4","2:3.4.2+dfsg-1","2:3.5.1+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_version":"2:3.5.1+dfsg-1","binary_name":"bison"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-24240.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"low"}]}