HOME VULNERABILITIESCVE-2021-36386

HIGH

CVE-2021-36386

CWE-909Published: July 30, 2021· Updated: Jun 17, 2026

7.5

CVSS v3.1

Official 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.

Technical Analysis

CVE-2021-36386 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Affected Vendors & Products

Fedora1 product(s)

fedora

fetchmail1 product(s)

fetchmail

Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttp://www.openwall.com/lists/oss-security/2021/07/28/5

PATCHhttp://www.openwall.com/lists/oss-security/2021/07/28/5

ADVISORYhttps://security.gentoo.org/glsa/202209-14

ADVISORYhttps://www.fetchmail.info/fetchmail-SA-2021-01.txt

ADVISORYhttps://www.fetchmail.info/security.html

ADVISORYhttps://security.gentoo.org/glsa/202209-14

ADVISORYhttps://www.fetchmail.info/fetchmail-SA-2021-01.txt

ADVISORYhttps://www.fetchmail.info/security.html

All References (14)

→

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

Quick Facts

CVE IDCVE-2021-36386

CVSS Score7.5 / 10

SeverityHIGH

WeaknessCWE-909

CISA KEVNo

Affected2 vendor(s)

PublishedJul 30, 2021

Related CVEs (CWE-909)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2021-36386 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

← All Vulnerabilities·Search for CVE-2021-36386·NVD