Vulnerability CVE-2020-24240


Published: 2020-08-25

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.

Type:

CWE-416

(Use After Free)

CVSS2 => (AV:N/AC:M/Au:N/C:N/I:N/A:C)

CVSS Base Score
Impact Subscore
Exploitability Subscore
7.1/10
6.9/10
8.6/10
Exploit range
Attack complexity
Authentication
Remote
Medium
No required
Confidentiality impact
Integrity impact
Availability impact
None
None
Complete
Affected software
GNU -> Bison 

 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

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