Vulnerability · Published Jan 19, 2022 · Assigned by mitre
CVE-2021-33913
Critical 9.8
In plain English
A critical-severity security flaw in the libspf2 package (Alpine). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 9.6% (higher than 96% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
libspf2 before 1.2.11 has a 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 SPF_record_expand_data in spf_expand.c. The amount of overflowed data depends on the relationship between the length of an entire domain name and the length of its leftmost label. 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | libspf2 | 1.2.11-r0 | ALPINE-CVE-2021-33913 |
| Alpine:v3.21 | libspf2 | 1.2.11-r0 | ALPINE-CVE-2021-33913 |
| Alpine:v3.22 | libspf2 | 1.2.11-r0 | ALPINE-CVE-2021-33913 |
| Alpine:v3.23 | libspf2 | 1.2.11-r0 | ALPINE-CVE-2021-33913 |
| Alpine:v3.24 | libspf2 | 1.2.11-r0 | ALPINE-CVE-2021-33913 |
| Debian:12 | libspf2 | 1.2.10-7.1 | DEBIAN-CVE-2021-33913 |
| Debian:13 | libspf2 | 1.2.10-7.1 | DEBIAN-CVE-2021-33913 |
| Debian:14 | libspf2 | 1.2.10-7.1 | DEBIAN-CVE-2021-33913 |