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Fencer Vulns
medium 4.9

CVE-2021-20266 json

A flaw was found in RPM's hdrblobInit() in lib/header.c.

published 2021-04-30 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7702

cvss
4.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

A flaw was found in RPM's hdrblobInit() in lib/header.c. This flaw allows an attacker who can modify the rpmdb to cause an out-of-bounds read. The highest threat from this vulnerability is to system availability.

Patch / fix

  • rpm rpm 4.16.1.3
  • rpm Debian 14, Debian 13, Debian 12 4.16.1.2+dfsg1-1

debian advisories DEBIAN-CVE-2021-20266

  • rpm Ubuntu Pro 18.04 LTS 4.14.1+dfsg1-2ubuntu0.1~esm1
  • rpm Ubuntu Pro 20.04 LTS 4.14.2.1+dfsg1-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-20266

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

  • rpm RHEL 8 4.14.3-19.el8
  • rpm-cron RHEL 8 4.14.3-19.el8
  • rpm-libs RHEL 8 4.14.3-19.el8
  • rpm-sign RHEL 8 4.14.3-19.el8
  • rpm-build RHEL 8 4.14.3-19.el8
  • python3-rpm RHEL 8 4.14.3-19.el8
  • rpm-apidocs RHEL 8 4.14.3-19.el8
  • rpm-build-libs RHEL 8 4.14.3-19.el8

red hat advisories RHSA-2021:4489

  • rpm SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.11.2-16.26.1
  • rpm-python SLES for SAP 12 SP5, SLES 12 SP5 4.11.2-16.26.1
  • python3-rpm SLES for SAP 12 SP5, SLES 12 SP5 4.11.2-16.26.1
  • rpm SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 +2 more 4.14.1-22.4.2
  • rpm-ndb SLE Module for Public Cloud 15 SP2 4.14.1-22.4.2
  • python-rpm SLE Module for Python 2 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 4.14.1-22.4.1
  • rpm SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3, Manager Server Module 4.2 +1 more 4.14.3-37.2
  • rpm-ndb SLE Module for Public Cloud 15 SP3 4.14.3-37.2

suse advisories SUSE-SU-2022:3939-1SUSE-SU-2021:3444-1SUSE-SU-2021:2682-1

  • rpm openSUSE Leap 15.2 4.14.1-lp152.18.3.1
  • python-rpm openSUSE Leap 15.2 4.14.1-lp152.18.3.1
  • rpm openSUSE Leap 15.3 4.14.3-37.2
  • rpm-ndb openSUSE Leap 15.3 4.14.3-37.2
  • python-rpm openSUSE Leap 15.3 4.14.3-37.2

opensuse advisories openSUSE-SU-2021:1366-1openSUSE-SU-2021:2682-1

  • rpm-build AlmaLinux 8 4.14.3-19.el8
  • rpm-plugin-fapolicyd AlmaLinux 8 4.14.3-19.el8

almalinux advisories ALSA-2021:4489

  • rpm Rocky Linux 8 4.14.3-19.el8

rocky linux advisories RLSA-2021:4489

  • rpm Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 4.16.1.3-r0

alpine advisories ALPINE-CVE-2021-20266

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-2021-20266 updated cvss 3.1

rpm: missing length checks in hdrblobInit()

  • Red Hat Enterprise Linux 6 rpm, rpm-cron, rpm-libs, rpm-build, rpm-python, rpm-apidocs Red Hat Enterprise Linux 7 rpm, rpm-cron, rpm-libs, rpm-sign, rpm-build, rpm-python, +3 more
    affected: workaround, no fix planned “If using the headerCheck() and headerImport() APIs in your software, do not run them on headers from untrusted sources.”
  • Red Hat Enterprise Linux AppStream (v. 8) rpm-build 4.14.3-19.el8, rpm-plugin-fapolicyd 4.14.3-19.el8 Red Hat Enterprise Linux BaseOS (v. 8) rpm 4.14.3-19.el8, rpm-cron 4.14.3-19.el8, rpm-libs 4.14.3-19.el8, rpm-sign 4.14.3-19.el8, python3-rpm 4.14.3-19.el8, rpm-apidocs 4.14.3-19.el8, +6 more
    fixed: vendor fix “If using the headerCheck() and headerImport() APIs in your software, do not run them on headers from untrusted sources.” RHSA-2021:4489
  • Red Hat Enterprise Linux 9 rpm, rpm-cron, rpm-libs, rpm-sign, rpm-build, python3-rpm, +9 more
    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

1.53% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

  • n/a rpm

Classification

Weakness

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.