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CVE-2021-33912

37
FAUCET Score

CVE-2021-33912 is a critical heap-based buffer overflow vulnerability in libspf2 versions prior to 1.2.11, affecting Debian and other systems utilizing this library for SPF record processing. This flaw, stemming from incorrect sprintf usage, could allow unauthenticated remote attackers to execute arbitrary code via a crafted SPF DNS record. With a CVSS score of 9.8 (CRITICAL), it presents a high risk of complete compromise (confidentiality, integrity, availability) with low attack complexity and no user interaction required. While there is no evidence of active exploitation, public exploit code, or KEV listing, the vulnerability has garnered significant community discussion, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.2.11CPE matchmatch criteria
cpe:2.3:a:libspf2_project:libspf2:*:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
9.64%
Probability of exploitation in next 30 days
EPSS Percentile
95.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0964 is in the 90th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / shevek/libspf2/tree/8131fe140704eaae695e76b5cd09e39bd1dd220b
Third Party Advisory
lists.debian.org / debian-lts-announce/2022/01/msg00015.html
Mailing ListThird Party Advisory
nathanielbennett.com / blog/libspf2-cve-jan-2022-disclosure
ExploitThird Party Advisory
security.gentoo.org / glsa/202401-22