MediumFix available
bison — security advisory
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.
- Products
- bison
- Affected versions
- Not specified
- Fixed versions
- 3.7.2-r0
- CVEs
- CVE-2020-24240
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 12:06 UTC · Revision 1
Source evidence
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.
osv:ALPINE-CVE-2020-24240
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
bison
Fixed versions: 3.7.2-r0
Complete source record
{
"id": "7f9d49983b5b647f406c2ba8cce2aa8ecca406319b3c48789590cb2e43aed563",
"url": "https://osv.dev/vulnerability/ALPINE-CVE-2020-24240",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ALPINE-CVE-2020-24240",
"summary": "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.",
"evidence": "osv:ALPINE-CVE-2020-24240",
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],
"severity": "medium",
"structured": {
"id": "ALPINE-CVE-2020-24240",
"aliases": [
"ALPINE-CVE-2020-24240"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
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],
"modified": "2026-10-26T11:17:55.148711104Z",
"provider": "osv",
"upstream": [
"CVE-2020-24240"
],
"references": [
"https://security.alpinelinux.org/vuln/CVE-2020-24240"
]
},
"related_cves": [
{
"value": "CVE-2020-24240",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 450514,
"published_at": "2020-08-25T14:15:16.543+00:00"
}