CVE-2021-27216

Arbitrary root file deletion via PID-file race

Published May 6, 2021 · Updated Aug 3, 2024

Race condition in Exim 4.94 through 4.94.1 allows local users to delete arbitrary files with root privileges via -oP or -oPX. delete_pid_file opens the supplied PID-file path and validates its contents, then unlinks that pathname without ensuring it still identifies the opened file. Any local account can replace the path between fopen and unlink, causing a chosen file to be deleted in root context.

CVSS severity6.3
Medium
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Exim 4.94 through 4.94.1 allows local users to delete arbitrary files with root privileges via -oP or -oPX. delete_pid_file opens the supplied PID-file path and validates its contents, then unlinks that pathname without ensuring it still identifies the opened file. Any local account can replace the path between fopen and unlink, causing a chosen file to be deleted in root context.

The record

CVE
CVE-2021-27216
Published
May 6, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362, CAPEC-29, CAPEC-26, T1485
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.3NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
6.3Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
6.3UbuntuCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
6.3NIST NVDAV:L/AC:M/Au:N/C:N/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 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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
CAPEC-26Leveraging Race Conditions
T1485Data Destruction

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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