CVE & CISA-KEV Catalog

CVE-2021-33913

CRITICALEPSS 95th pctl
9.8
CVSS v3
NVD

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.

CWE-787Out-of-bounds Write

How to fix

Remediation Available
libspf2Debian
Fixed in:1.2.10-7.1~deb11u1CVE-2021-33913
Fixed in:1.2.10-7.1CVE-2021-33913
Fixed in:1.2.10-7.1CVE-2021-33913
Fixed in:1.2.10-7.1CVE-2021-33913
libmail-spf-xs-perlUbuntu
Fixed in:1.2.10-6ubuntu0.1~esm1USN-6584-1
Fixed in:1.2.10-6ubuntu0.1~esm2USN-6584-2
Fixed in:1.2.10-7ubuntu0.18.04.1~esm1USN-6584-1
Fixed in:1.2.10-7+deb9u2build0.20.04.1USN-6584-1
libspf2Ubuntu
Fixed in:1.2.10-6ubuntu0.1~esm2USN-6584-2
Fixed in:1.2.10-6ubuntu0.1~esm1USN-6584-1
Fixed in:1.2.10-7ubuntu0.18.04.1~esm1USN-6584-1
Fixed in:1.2.10-7+deb9u2build0.20.04.1USN-6584-1
libspf2-2Ubuntu
Fixed in:1.2.10-6ubuntu0.1~esm1USN-6584-1
Fixed in:1.2.10-6ubuntu0.1~esm2USN-6584-2
Fixed in:1.2.10-7ubuntu0.18.04.1~esm1USN-6584-1
Fixed in:1.2.10-7+deb9u2build0.20.04.1USN-6584-1
libspf2-devUbuntu
Fixed in:1.2.10-6ubuntu0.1~esm1USN-6584-1
Fixed in:1.2.10-6ubuntu0.1~esm2USN-6584-2
Fixed in:1.2.10-7ubuntu0.18.04.1~esm1USN-6584-1
Fixed in:1.2.10-7+deb9u2build0.20.04.1USN-6584-1
spfqueryUbuntu
Fixed in:1.2.10-6ubuntu0.1~esm1USN-6584-1
Fixed in:1.2.10-6ubuntu0.1~esm2USN-6584-2
Fixed in:1.2.10-7ubuntu0.18.04.1~esm1USN-6584-1
Fixed in:1.2.10-7+deb9u2build0.20.04.1USN-6584-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

9.64%probability of exploitation in 30 days
95thpercentile

High risk: more likely to be exploited than 95% of all known CVEs.

References

Third-Party Advisory2
Other references1

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2025-22457Critical9.0100%KEV + RansomFix
CVE-2025-0282Critical9.0100%KEV + Ransom-
CVE-2015-3113Critical9.8100%KEVFix
CVE-2021-20038Critical9.8100%KEV + Ransom-
CVE-2023-4863High8.8100%KEVFix
CVE-2020-16040Medium6.5100%-Fix
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.