{"cve":"CVE-2020-24240","nvd":{"published":"2020-08-25T14:15:16.543","modified":"2026-06-17T03:05:19.940","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-416"],"references":["https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68d","https://github.com/akimd/bison/compare/v3.7...v3.7.1","https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html","https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68d","https://github.com/akimd/bison/compare/v3.7...v3.7.1"],"products":["gnu:bison"],"source":"nvd","synced_at":"2026-10-19T21:09:20.498348299+00:00"},"epss":{"cve":"CVE-2020-24240","score":0.01275,"percentile":0.69939,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}