Skip to content
Fencer Vulns
medium 5.5

CVE-2021-3429 json

sensitive data exposure in cloud-init logs

published 2023-04-19 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26755

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

When instructing cloud-init to set a random password for a new user account, versions before 21.2 would write that password to the world-readable log file /var/log/cloud-init-output.log. This could allow a local user to log in as another user.

Patch / fix

  • Canonical Ltd. cloud-init 21.2
  • cloud-init Debian 14, Debian 13, Debian 12 20.4.1-2

debian advisories DEBIAN-CVE-2021-3429

  • cloud-init Ubuntu 16.04 LTS 21.1-19-gbad84ad4-0ubuntu1~16.04.1
  • cloud-init Ubuntu 18.04 LTS 21.1-19-gbad84ad4-0ubuntu1~18.04.1
  • cloud-init Ubuntu 20.04 LTS 21.1-19-gbad84ad4-0ubuntu1~20.04.1

ubuntu advisories UBUNTU-CVE-2021-3429

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • cloud-init RHEL 8 20.3-10.el8_4.5
  • cloud-init RHEL 8.2 EUS 18.5-12.el8_2.10
  • cloud-init RHEL 8.1 EUS 18.5-7.el8_1.6

red hat advisories RHSA-2021:3371RHSA-2021:3177RHSA-2021:3081

  • cloud-init SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4, SLE Module for Public Cloud 15 SP3 +4 more 23.1-150100.8.66.1
  • cloud-init SLE Module for Public Cloud 12 20.2-37.57.1

suse advisories SUSE-FU-2023:3283-1SUSE-SU-2023:2164-1

  • cloud-init openSUSE Tumbleweed 23.1-2.1

opensuse advisories openSUSE-SU-2024:13053-1

  • cloud-init Rocky Linux 8 20.3-10.el8_4.5

rocky linux advisories RLSA-2021:3081

  • cloud-init Alpine 3.13 20.4.1-r1
  • cloud-init Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 21.1-r1

alpine advisories ALPINE-CVE-2021-3429

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

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-2021-3429 updated cvss 5.5

cloud-init: randomly generated passwords logged in clear-text to world-readable file

  • Red Hat Enterprise Linux 6 cloud-init Red Hat Enterprise Linux 7 cloud-init
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) cloud-init 20.3-10.el8_4.5
    fixed: vendor fix RHSA-2021:3081
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) cloud-init 18.5-7.el8_1.6
    fixed: vendor fix RHSA-2021:3177
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) cloud-init 18.5-12.el8_2.10
    fixed: vendor fix RHSA-2021:3371
  • Red Hat Enterprise Linux 9 cloud-init
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
21 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected products

  • Canonical Ltd. cloud-init

Classification

Weakness
  • CWE-532 Insertion of Sensitive Information into Log File

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.