CVE-2020-24240 — MEDIUM (5.5)

Vulnerability 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 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

NONE

Integrity

NONE

Availability

HIGH

Affected Products

Vendor	Product	Versions
Gnu	Bison	3.7

Related Weaknesses (CWE)

CWE-416

References

https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68dPatchThird Party Advisory
https://github.com/akimd/bison/compare/v3.7...v3.7.1Third Party Advisory
https://lists.gnu.org/r/bug-bison/2020-07/msg00051.htmlMailing ListVendor Advisory
https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68dPatchThird Party Advisory
https://github.com/akimd/bison/compare/v3.7...v3.7.1Third Party Advisory
https://lists.gnu.org/r/bug-bison/2020-07/msg00051.htmlMailing ListVendor Advisory

FAQ

What is CVE-2020-24240?

CVE-2020-24240 is a vulnerability with a CVSS score of 5.5 (MEDIUM). 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, ...

How severe is CVE-2020-24240?

CVE-2020-24240 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2020-24240?

Check the references section above for vendor advisories and patch information. Affected products include: Gnu Bison.