Medium [CVE-2026-72225] fix integer underflow in jbd2_journal_initialize_fast_commit
This medium-severity Red Hat Linux advisory covers CVE-2026-72225 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() jbd2_journal_initialize_fast_commit() validates journal capacity by checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS).
Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds j_last the subtraction wraps to a large value, bypassing the bounds check. The resulting underflow corrupts j_last, j_fc_first, and j_free, leading to journal abort.
Fix by checking num_fc_blks against j_last before the subtraction, returning -EFSCORRUPTED. A flaw was found in the Linux kernel's jbd2 journaling layer.
This issue can result in a Denial of Service (DoS) for the affected system. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-191. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 9.
Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
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