Description
A flaw was found in sudo. When sudoers rules use NOTBEFORE or NOTAFTER time-based access restrictions with timestamps that omit the trailing 'Z' timezone indicator, the time evaluation relies on the TZ environment variable inherited from the calling user. Because sudo is a setuid-root program, an unprivileged local user can set TZ to an extreme timezone offset to shift the authorization window by up to approximately 25 hours, causing expired rules to be treated as valid. This allows the user to execute commands outside the intended time window. Authentication is not bypassed; only the time-based authorization check is affected.
Published: 2026-09-23
Score: 7.8 High
EPSS: n/a
KEV: No
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Remediation

Vendor Workaround

Append the 'Z' timezone suffix to all NOTBEFORE and NOTAFTER timestamps in sudoers rules. For example, change 'NOTAFTER=20261231235959' to 'NOTAFTER=20261231235959Z'. Timestamps with the 'Z' suffix are interpreted as UTC via timegm() and are not affected by the TZ environment variable. Administrators can audit their sudoers configuration with: grep -rE 'NOT(BEFORE|AFTER)=' /etc/sudoers /etc/sudoers.d/ and verify that all timestamps end with 'Z'.

Tracking

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Advisories

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History

Wed, 23 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8

Wed, 23 Sep 2026 13:45:00 +0000

Type Values Removed Values Added
Description A flaw was found in sudo. When sudoers rules use NOTBEFORE or NOTAFTER time-based access restrictions with timestamps that omit the trailing 'Z' timezone indicator, the time evaluation relies on the TZ environment variable inherited from the calling user. Because sudo is a setuid-root program, an unprivileged local user can set TZ to an extreme timezone offset to shift the authorization window by up to approximately 25 hours, causing expired rules to be treated as valid. This allows the user to execute commands outside the intended time window. Authentication is not bypassed; only the time-based authorization check is affected.
Title Sudo: sudo: tz environment variable allows bypass of notbefore/notafter time-based authorization
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Weaknesses CWE-863
CPEs cpe:/a:redhat:hummingbird:1
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Subscriptions

Redhat Enterprise Linux Hummingbird
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-09-23T14:09:42.060Z

Reserved: 2026-09-23T10:31:55.548Z

Link: CVE-2026-96512

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-23T14:17:10.747

Modified: 2026-09-23T15:17:32.997

Link: CVE-2026-96512

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-23T15:30:07Z

Weaknesses