CVE-2021-20266Network attack vector

Process crash via unchecked header lengths

Published Apr 30, 2021 · Updated Aug 3, 2024

Out-of-bounds read in RPM Package Manager 4.17.0 allows attackers who can modify the rpmdb to crash RPM processes. hdrblobInit() in lib/header.c reads untrusted index and data lengths and calculates the blob layout without first proving those fields fit within the supplied buffer. Reachability requires write access to the RPM database; the documented consequence is an availability loss from a crashing RPM operation, not data disclosure or modification.

CVSS severity4.9
Medium
EPSS probability1.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in RPM Package Manager 4.17.0 allows attackers who can modify the rpmdb to crash RPM processes. hdrblobInit() in lib/header.c reads untrusted index and data lengths and calculates the blob layout without first proving those fields fit within the supplied buffer. Reachability requires write access to the RPM database; the documented consequence is an availability loss from a crashing RPM operation, not data disclosure or modification.

The record

CVE
CVE-2021-20266
Published
Apr 30, 2021
Updated
Aug 3, 2024
Vendor
RPM Software Management
Product
RPM Package Manager
Classifications
CWE-125, T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Apr 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=rpm 4.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

RPM Software Management · RPM Package Managerversion=rpm 4.17.0

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
4.9NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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