CVE-2021-36386

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.

Published: 2021-07-30 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-36386 is rated Moderate Risk (61.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.56%). EPSS rose +2.30% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-36386

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.26% 2.56% +2.30%
2 2025-11-21 1.44% 0.26% -1.18%
3 2025-11-18 — 1.44% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-36386

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-36386

OS Trackers for CVE-2021-36386

vendor priority summary link
alpine high CVE-2021-36386: 1 source package rows (fetchmail); 9 state rows across 9 repos (3.11-main, 3.12-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 2. https://security.alpinelinux.org/vuln/CVE-2021-36386
debian unimportant CVE-2021-36386 unimportant priority: Debian including 1 source packages (fetchmail), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-36386
gentoo low CVE-2021-36386: 1 GLSA(s) (202209-14), 1 atom(s) (net-mail/fetchmail); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-36386
redhat medium — https://access.redhat.com/security/cve/CVE-2021-36386
suse medium CVE-2021-36386 severity moderate: SUSE including 18 source package names (fetchmail-6.3.26-13.12.1, fetchmail-6.3.26-13.18.1, …), 80 product×package rows across 47 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 5, … (47 product lines)): Fixed 80. https://www.suse.com/security/cve/CVE-2021-36386/
ubuntu low CVE-2021-36386 low priority: Ubuntu including 1 source packages (fetchmail), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 9, needs-triage 3, DNE 1, ignored 1, released 1. https://ubuntu.com/security/CVE-2021-36386

Affected software / configurations for CVE-2021-36386

Vendor Product Version Raw CPE
fetchmail fetchmail < 6.4.20 cpe:2.3:a:fetchmail:fetchmail:*:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

References for CVE-2021-36386

cvelogic Threat Intelligence