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Fencer Vulns
high 8.8

CVE-2021-27927 json

In Zabbix from 4.0.x before 4.0.28rc1, 5.0.0alpha1 before 5.0.10rc1, 5.2.x before 5.2.6rc1, and 5.4.0alpha1 before 5.4.0beta2, the CControl…

published 2021-03-03 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-14647

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

In Zabbix from 4.0.x before 4.0.28rc1, 5.0.0alpha1 before 5.0.10rc1, 5.2.x before 5.2.6rc1, and 5.4.0alpha1 before 5.4.0beta2, the CControllerAuthenticationUpdate controller lacks a CSRF protection mechanism. The code inside this controller calls diableSIDValidation inside the init() method. An attacker doesn't have to know Zabbix user login credentials, but has to know the correct Zabbix URL and contact information of an existing user with sufficient privileges.

Patch / fix

  • zabbix Debian 14, Debian 13, Debian 12 1:5.0.8+dfsg-1

debian advisories DEBIAN-CVE-2021-27927

  • zabbix SLES for SAP 12 SP5, SLES 12 SP5 4.0.12-4.12.1

suse advisories SUSE-SU-2021:0990-1

  • zabbix openSUSE Leap 15.3 4.0.37-lp153.2.3.1

opensuse advisories openSUSE-SU-2022:0036-1

  • zabbix Alpine 3.12 5.0.9-r0
  • zabbix Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 5.2.6-r0

alpine advisories ALPINE-CVE-2021-27927

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

  • zabbix-frontend-php Arch Linux 5.2.6-1

arch linux advisories AVG-1771

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-2021-27927 updated

zabbix: CControllerAuthenticationUpdate controller lacks a CSRF protection mechanism

  • Red Hat All currently supported Red Hat products
    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

2.20% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-352 Cross-Site Request Forgery

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.