Medium severity · published Aug 25, 2020
CVE-2020-24240
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
5.5
CVSS
1.3%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.3% · higher than 70% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BI
Bison · Gnu
3.7 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-24240
CVE.org
https://www.cve.org/CVERecord?id=CVE-2020-24240
Patch
https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68d
Third Party Advisory
https://github.com/akimd/bison/compare/v3.7...v3.7.1
Mailing List
https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html
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