Use-after-free in bison (Alpine package)

1) Use-after-free

EUVDB-ID: #VU46310

Risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-24240

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.

GNU Bison before 3.7.1 has a use-after-free in _obstack_free in lib/obstack.c (called from gram_lex) when a '�' 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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

bison (Alpine package): 3.7.1-r0

CPE2.3

• cpe:2.3:a:alpine:bison_alpine_package:3.7.1-r0:*:*:*:*:alpine_linux:*:3.12

External links

https://git.alpinelinux.org/aports/commit/?id=9bdba8a23127bd78dd9a3bf93745b32b17a7271f

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.