CVE-2026-72225 (GCVE-0-2026-72225)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-23 12:47
VLAI
Title
jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < aa90f00932bf572d6ef284c977c2a60b39c13bd6 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < e144ad0250f77e23e28949587b8b57e40dc3b512 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < 4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < fb9b49618ed7296ebfad62a3835da8945f727001 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < 4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < 78955fdce8ff654e6d33a2fa90882a1e7eb26330 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < a58fc10adf503969fec2007b5afe8987258046c4 (git)
Affected: 6866d7b3f2bb4f011041ba54c98b1584497fe2fd , < 289a2ca0c9b7eae74f93fc213b0b971669b8683d (git)
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Linux Linux Affected: 5.10
Unaffected: 0 , < 5.10 (semver)
Unaffected: 5.10.266 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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        }
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            "version": "3.1"
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              "value": "AV:L - The vulnerable code is reached only via the ext4 mount path (mount/fsopen syscall) when enabling JBD2 fast commit in jbd2_journal_set_features(); it is not reachable through network-facing kernel services.\nAC:L - An attacker who can mount a crafted ext4 image fully controls journal superblock fields (s_num_fc_blks vs s_maxlen) and can reliably trigger the underflow on first-time fast-commit enable without races or rare kernel configs.\nPR:L - Triggering ext4 mount of a malicious image requires CAP_SYS_ADMIN, which an unprivileged local user can obtain inside a user/mount namespace (e.g. unshare -Urm) to mount loop-backed ext4 with fast_commit enabled.\nUI:N - Exploitation does not require a separate victim action beyond the attacker (or their namespace) performing the mount of the prepared filesystem image; no additional user interaction is needed.\nS:U - Impact is confined to journal/ext4 corruption and I/O within the mounting kernel context; it does not cross a VM, container, or IOMMU security boundary to affect a separate authority.\nC:H - Corrupted j_last/j_fc_first/j_free values drive subsequent jbd2_journal_bmap and journal I/O with attacker-influenced block indices, enabling out-of-bounds reads from the journal backing device and potential kernel memory disclosure.\nI:H - The same corrupted journal geometry can direct journal block allocations and writes to incorrect offsets on the backing block device, constituting exploitable metadata corruption with integrity impact beyond a simple error return.\nA:H - The fix commit and jbd2 abort path confirm the corruption leads to journal abort and mount/operational failure; repeated mounting of malicious images can deny filesystem availability and force recovery or remount-readonly."
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    "datePublished": "2026-08-15T05:54:17.541Z",
    "dateReserved": "2026-08-09T03:40:39.913Z",
    "dateUpdated": "2026-08-23T12:47:03.674Z",
    "state": "PUBLISHED"
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\njbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()\n\njbd2_journal_initialize_fast_commit() validates journal capacity by\nchecking (journal-\u003ej_last - num_fc_blks \u003c JBD2_MIN_JOURNAL_BLOCKS).\nBoth j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds\nj_last the subtraction wraps to a large value, bypassing the bounds\ncheck.\n\nThe resulting underflow corrupts j_last, j_fc_first, and j_free,\nleading to journal abort.\n\nFix by checking num_fc_blks against j_last before the subtraction,\nreturning -EFSCORRUPTED."
          }
        ],
        "id": "CVE-2026-72225",
        "lastModified": "2026-08-23T13:16:41.947",
        "metrics": {
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                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
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                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-08-15T06:21:41.487",
        "references": [
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        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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    "redhat_vex": {
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      "current_release_date": "2026-08-19T05:26:06+00:00",
      "cve": "CVE-2026-72225",
      "id": "CVE-2026-72225",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72225.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-31T16:27:00Z",
      "cve": "CVE-2026-72225",
      "id": "CVE-2026-72225",
      "initial_release_date": "2026-08-31T16:27:00Z",
      "product_status:known_affected": "178",
      "product_status:known_not_affected": "184",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72225",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72225.json",
      "version": "2"
    }
  }
}



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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.