CVE-2026-18477

Summary

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat Enterprise Linux 102:1.35-13.el10_2 < *unaffected
Red HatRed Hat Enterprise Linux 92:1.34-13.el9_8 < *unaffected
Red HatRed Hat Discovery 21788205779 < *unaffected
Red HatRed Hat Hardened Images1.35-9.1.hum1 < *unaffected
Red HatRed Hat Update Infrastructure 51788880445 < *unaffected
Red HatRed Hat Update Infrastructure 51788880464 < *unaffected
Red HatRed Hat Update Infrastructure 51788880456 < *unaffected
Red HatRed Hat Update Infrastructure 51788765051 < *unaffected
Red HatRed Hat Update Infrastructure 51788880581 < *unaffected

Weaknesses

  • CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

Workarounds

Do not perform incremental restores (-G/-g) from untrusted archives. Avoid restoring incremental backups on systems where untrusted users have shell access,​ perform restoration only on systems inaccessible to users.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References