CriticalFix available
libspf2 — security advisory
libspf2 before 1.2.11 has a four-byte heap-based buffer overflow that might allow remote attackers to execute arbitrary code (via an unauthenticated e-mail message from anywhere on the Internet) with a crafted SPF DNS record, because of incorrect sprintf usage in SPF_record_expand_data in spf_expand.c. The vulnerable code may be part of the supply chain of a site's e-mail infrastructure (e.g., with additional configuration, Exim can use libspf2; the Postfix web site links to unofficial patches for use of libspf2 with Postfix; older versions of spfquery relied on libspf2) but most often is not.
- Products
- libspf2
- Affected versions
- Not specified
- Fixed versions
- 1.2.11-r0
- CVEs
- CVE-2021-33912
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 22:05 UTC · Revision 1
Source evidence
libspf2 before 1.2.11 has a four-byte heap-based buffer overflow that might allow remote attackers to execute arbitrary code (via an unauthenticated e-mail message from anywhere on the Internet) with a crafted SPF DNS record, because of incorrect sprintf usage in SPF_record_expand_data in spf_expand.c. The vulnerable code may be part of the supply chain of a site's e-mail infrastructure (e.g., with additional configuration, Exim can use libspf2; the Postfix web site links to unofficial patches for use of libspf2 with Postfix; older versions of spfquery relied on libspf2) but most often is not.
osv:ALPINE-CVE-2021-33912
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
libspf2
Fixed versions: 1.2.11-r0
Complete source record
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"url": "https://osv.dev/vulnerability/ALPINE-CVE-2021-33912",
"method": "structured",
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"modified": "2026-10-23T17:17:56.191314506Z",
"provider": "osv",
"upstream": [
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"references": [
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]
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"source_id": "core-osv",
"document_id": 415460,
"published_at": "2022-01-19T18:15:07.783+00:00"
}