CVE-2021-20314

CRITICALNVD 9.89.8—

9.8

Stack buffer overflow in libspf2 versions below 1.2.11 when processing certain SPF macros can lead to Denial of service and potentially code execution via malicious crafted SPF explanation messages.

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 37.9%
KEV: Not listed

Published

August 12, 2021

Last Modified

November 21, 2024

Advisory Details (5)

Auto-updated May 30, 2026

Patch available. Sources: redhat.

generic

libspf2: Multiple vulnerabilities (GLSA 202401-22) — Gentoo security

https://security.gentoo.org/glsa/202401-22

generic

[SECURITY] Fedora 33 Update: libspf2-1.2.11-1.20210922git4915c308.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y6T4HYXXSUQCGJB2ES6X7Q74YYF7V7XU/

generic

[SECURITY] Fedora 34 Update: libspf2-1.2.11-1.20210922git4915c308.fc34 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GFXJRHPE5OSCPTNA3ZZ4ORDHT4JQH3Y4/

generic

[SECURITY] Fedora 35 Update: libspf2-1.2.11-1.20210922git4915c308.fc35 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMSFT2NJDZ7PATRZSQPAOGSE7JD6ELOB/

redhat Patch Available

1993070 – (CVE-2021-20314) CVE-2021-20314 libspf2: stack buffer overflow when processing SPF explanation macros

https://bugzilla.redhat.com/show_bug.cgi?id=1993070

Patch Availability(1)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	spfquery (1.2.10-6ubuntu0.1~esm1) @ xenial	2026-05-26	ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-787Out-of-bounds Write

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

UbuntuUSN-6584-1MEDIUM
Libspf2 vulnerabilities

Data Freshness Timeline

(refreshed 13× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-08 14:15 UTCEPSS rescore
2026-06-08 14:15 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:08 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-20314?

CVE-2021-20314 is a critical vulnerability published on August 12, 2021. Stack buffer overflow in libspf2 versions below 1.2.11 when processing certain SPF macros can lead to Denial of service and potentially code execution via malicious crafted SPF explanation messages.

When was CVE-2021-20314 disclosed?

CVE-2021-20314 was first published in the National Vulnerability Database on August 12, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-20314 actively exploited?

CVE-2021-20314 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-20314?

CVE-2021-20314 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2021-20314?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-20314, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-20314

Explore →

Is Your Infrastructure Affected by CVE-2021-20314?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2021-20314

Published

Last Modified

Advisory Details (5)

libspf2: Multiple vulnerabilities (GLSA 202401-22) — Gentoo security

[SECURITY] Fedora 33 Update: libspf2-1.2.11-1.20210922git4915c308.fc33 - package-announce - Fedora mailing-lists

[SECURITY] Fedora 34 Update: libspf2-1.2.11-1.20210922git4915c308.fc34 - package-announce - Fedora mailing-lists

[SECURITY] Fedora 35 Update: libspf2-1.2.11-1.20210922git4915c308.fc35 - package-announce - Fedora mailing-lists

1993070 – (CVE-2021-20314) CVE-2021-20314 libspf2: stack buffer overflow when processing SPF explanation macros

Patch Availability(1)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-20314?

Same vendor

Same CWE

CVE-2021-20314

📅 Published

🔄 Last Modified

📋 Advisory Details (5)

libspf2: Multiple vulnerabilities (GLSA 202401-22) — Gentoo security

[SECURITY] Fedora 33 Update: libspf2-1.2.11-1.20210922git4915c308.fc33 - package-announce - Fedora mailing-lists

[SECURITY] Fedora 34 Update: libspf2-1.2.11-1.20210922git4915c308.fc34 - package-announce - Fedora mailing-lists

[SECURITY] Fedora 35 Update: libspf2-1.2.11-1.20210922git4915c308.fc35 - package-announce - Fedora mailing-lists

1993070 – (CVE-2021-20314) CVE-2021-20314 libspf2: stack buffer overflow when processing SPF explanation macros

Patch Availability(1)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-20314?

🔗 Related CVEs(same vendor + same CWE)

Same vendor

Same CWE

Published

Last Modified

Advisory Details (5)

Frequently asked(5)

Related CVEs(same vendor + same CWE)