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CVE-2020-24240

MEDIUM
5.5
CVSS Score
Published: August 25, 2020 at 01:45 PM UTC
Updated: June 17, 2026 at 03:05 AM UTC
1 product affected across 1 vendorBison

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Severity
MEDIUM5.5
Exploit prediction
EPSS 1%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/akimd/bison/commit/be95a4fe2951374676efc9454ffee8638faaf68d
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://github.com/akimd/bison/compare/v3.7...v3.7.1
x_refsource_MISCMailing ListVendor Advisory
Source: [email protected]
https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html

CVSS

5.5MEDIUM[email protected]
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-416

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