CVE-2025-27591Public exploit

Local root escalation via symlink-following log chmod

Published Mar 11, 2025 · Updated Mar 21, 2025

Privilege escalation in Meta Platforms, Inc. below before 0.9.0 allows local users to gain root privileges through a symlink attack. The root-run service creates /var/log/below with mode 0777, then follows a user-controlled error_root.log symlink and applies mode 0666 to its target. Any local account that can replace the predictable log path before a privileged service run can make a sensitive file such as /etc/shadow world-writable and obtain root access.

CVSS severity7.8
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in Meta Platforms, Inc. below before 0.9.0 allows local users to gain root privileges through a symlink attack. The root-run service creates /var/log/below with mode 0777, then follows a user-controlled error_root.log symlink and applies mode 0666 to its target. Any local account that can replace the predictable log path before a privileged service run can make a sensitive file such as /etc/shadow world-writable and obtain root access.

The record

CVE
CVE-2025-27591
Published
Mar 11, 2025
Updated
Mar 21, 2025
Vendor
Meta Platforms, Inc.
Product
below
Classifications
CWE-732, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 21, 2025Record 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=0.0.0 <0.9.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Meta Platforms, Inc. · belowversion=0.0.0 <0.9.0

Published CVSS scores

7.8Meta Platforms, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

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 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 exploitPublished

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
T1068Exploitation for Privilege Escalation

Public exploit references

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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