CVE-2021-36386

Name: CVE-2021-36386
Creator: NVD / NIST
Published: 2021-07-30T14:15:18.14+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.56%

Last modified Jun 17, 2026

CVE-2021-36386 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. report_vbuild in report.c in Fetchmail before 6.4.20 sometimes omits initialization of the vsnprintf va_list argument, which might allow mail servers to cause a denial of service or possibly have unspecified other impact via long error messages. NOTE: it is unclear whether use of Fetchmail on any realistic platform results in an impact beyond an inconvenience to the client user.. EPSS estimates a 2.56% chance of exploitation in the next 30 days.

Description

report_vbuild in report.c in Fetchmail before 6.4.20 sometimes omits initialization of the vsnprintf va_list argument, which might allow mail servers to cause a denial of service or possibly have unspecified other impact via long error messages. NOTE: it is unclear whether use of Fetchmail on any realistic platform results in an impact beyond an inconvenience to the client user.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.56%

83.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-909

Affected Software

Vendor	Product	Versions
Fetchmail	Fetchmail	< 6.4.20
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34

References

http://www.openwall.com/lists/oss-security/2021/07/28/5Mailing List, Patch, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/09/1Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AGYO5AHSXTCKA4NQC2Z4H3XMMYNAGC77/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OIXKO6QW3AUHGJVWKJXBCOVBYJUJRBFC/
https://security.gentoo.org/glsa/202209-14Third Party Advisory
https://www.fetchmail.info/fetchmail-SA-2021-01.txtVendor Advisory
https://www.fetchmail.info/security.htmlVendor Advisory
http://www.openwall.com/lists/oss-security/2021/07/28/5Mailing List, Patch, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/09/1Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AGYO5AHSXTCKA4NQC2Z4H3XMMYNAGC77/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OIXKO6QW3AUHGJVWKJXBCOVBYJUJRBFC/
https://security.gentoo.org/glsa/202209-14Third Party Advisory
https://www.fetchmail.info/fetchmail-SA-2021-01.txtVendor Advisory
https://www.fetchmail.info/security.htmlVendor Advisory

Timeline

Published: Jul 30, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-36386?

How severe is CVE-2021-36386?

CVE-2021-36386 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.56% probability of exploitation in the next 30 days.

How do I fix CVE-2021-36386?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-36386?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST