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Fencer Vulns
high 7.5

CVE-2021-36386 json

report_vbuild in report.c in Fetchmail before 6.4.20 sometimes omits initialization of the vsnprintf va_list argument, which might allow ma…

published 2021-07-29 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-23001

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.6%
EPSS 2.6% chance of exploitation in 30 days, percentile 85%
public exploits
0
none known

Summary

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.

Patch / fix

  • fetchmail fetchmail 6.4.20
  • fetchmail Debian 14, Debian 13, Debian 12 6.4.16-4

debian advisories DEBIAN-CVE-2021-36386

  • fetchmail RHEL 8 6.4.24-1.el8

red hat advisories RHSA-2022:1964

  • fetchmail SLES for SAP 12 SP5, SLES 12 SP5 6.3.26-13.18.1
  • fetchmail SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +11 more 6.4.22-20.20.1
  • fetchmail SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +14 more 6.3.26-20.14.1
  • fetchmail SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +8 more 6.3.26-13.12.1

suse advisories SUSE-SU-2024:3006-1SUSE-SU-2021:4018-1SUSE-SU-2021:2791-1SUSE-SU-2021:2771-1

  • fetchmail openSUSE Tumbleweed 6.4.21-2.1
  • fetchmail openSUSE Leap 15.2 6.4.22-lp152.6.12.1
  • fetchmail openSUSE Leap 15.3 6.4.22-20.20.1
  • fetchmail openSUSE Leap 15.2 6.3.26-lp152.6.6.1
  • fetchmail openSUSE Leap 15.3 6.3.26-20.14.1

opensuse advisories openSUSE-SU-2024:10753-1openSUSE-SU-2021:1591-1openSUSE-SU-2021:4018-1openSUSE-SU-2021:1183-1openSUSE-SU-2021:2791-1

  • fetchmail AlmaLinux 8 6.4.24-1.el8

almalinux advisories ALSA-2022:1964

  • fetchmail Rocky Linux 8 6.4.24-1.el8

rocky linux advisories RLSA-2022:1964

  • fetchmail Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 6.4.20-r0

alpine advisories ALPINE-CVE-2021-36386

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • fetchmail CBL-Mariner 2.0 6.4.22-1

azure linux advisories AZL-7226

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • fetchmail Arch Linux 6.4.21-1

arch linux advisories AVG-2238

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-36386 updated cvss 7.5

fetchmail: DoS or information disclosure when logging long messages

  • Red Hat Enterprise Linux 6 fetchmail Red Hat Enterprise Linux 7 fetchmail
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) fetchmail 6.4.24-1.el8
    fixed: vendor fix RHSA-2022:1964
  • Red Hat Enterprise Linux 9 fetchmail
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.56% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-909 Missing Initialization of Resource

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.