CVE-2021-35939

Local root escalation via intermediate symlink traversal

Published Aug 26, 2022 · Updated Aug 4, 2024

Improper link resolution in RPM Package Manager before 4.18.0 allows local users to gain root privileges during package installation. The file-state machine in lib/fsm.c resolves installation paths without validating every intermediate symlink, allowing an attacker-controlled ancestor directory to redirect privileged file creation. Exploitation requires control of an ancestor directory used by a privileged RPM transaction and can modify root-owned files, exposing the system to root-level compromise.

CVSS severity6.7
Medium
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper link resolution in RPM Package Manager before 4.18.0 allows local users to gain root privileges during package installation. The file-state machine in lib/fsm.c resolves installation paths without validating every intermediate symlink, allowing an attacker-controlled ancestor directory to redirect privileged file creation. Exploitation requires control of an ancestor directory used by a privileged RPM transaction and can modify root-owned files, exposing the system to root-level compromise.

The record

CVE
CVE-2021-35939
Published
Aug 26, 2022
Updated
Aug 4, 2024
Vendor
RPM Software Management
Product
RPM Package Manager
Classifications
CWE-59, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 26, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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  1. Affected versionversion=Fixed in RPM-v4.18

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

RPM Software Management · RPM Package Managerversion=Fixed in RPM-v4.18

Published CVSS scores

6.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1068Exploitation for Privilege Escalation

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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