CVE-2021-25261

SYSTEM code execution via updater symlink manipulation

Published Jun 15, 2022 · Updated Aug 3, 2024

Local privilege escalation in Yandex Browser for Windows before 22.5.0.862 allows local users to execute code with SYSTEM privileges. During an update, the installer follows attacker-controlled symbolic links when accessing an installation file, redirecting its privileged file operation to an unintended target. A low-privileged local account and a browser update are required; successful exploitation grants full SYSTEM-level code execution.

CVSS severity7.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Local privilege escalation in Yandex Browser for Windows before 22.5.0.862 allows local users to execute code with SYSTEM privileges. During an update, the installer follows attacker-controlled symbolic links when accessing an installation file, redirecting its privileged file operation to an unintended target. A low-privileged local account and a browser update are required; successful exploitation grants full SYSTEM-level code execution.

The record

CVE
CVE-2021-25261
Published
Jun 15, 2022
Updated
Aug 3, 2024
Vendor
Yandex
Product
Yandex Browser
Classifications
CWE-59, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 2022CVE 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=All versions prior to version 22.5.0.862

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Yandex · Yandex Browserversion=All versions prior to version 22.5.0.862

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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