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CVE-2026-46046 Linux CVE debrief

A buffer reference leak vulnerability exists in the Linux kernel's ext4 filesystem implementation. The flaw occurs in `ext4_xattr_inode_dec_ref_all()` where `ext4_get_inode_loc()` acquires `iloc.bh` (a buffer head), but this buffer is never released via `brelse()` when `block_csum` is false. This was introduced by commit c8e008b60492 (ext4: ignore xattrs past end). The missing buffer release leads to a reference count leak, which can contribute to resource exhaustion over time. Multiple stable kernel branches have received fixes.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-06-16
Advisory published
2026-05-27
Advisory updated
2026-06-16

Who should care

Linux system administrators, kernel maintainers, and organizations running ext4 filesystems on production systems

Technical summary

The ext4_xattr_inode_dec_ref_all() function in the Linux kernel fails to release a buffer head obtained via ext4_get_inode_loc() when block_csum is false. This results in a buffer reference count leak that can lead to resource exhaustion. The vulnerability was introduced by commit c8e008b60492 and affects systems using ext4 extended attributes.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel updates from your Linux distribution that include the referenced stable kernel commits
  • Monitor for ext4 filesystem resource exhaustion indicators on affected systems
  • Verify kernel version includes fix commits: 097227f1ffe1a85bc3c359f81c71e3d40e06e920, 1bc1107a3a403a6d440673ed6666f7b07ef868a8, 1e6b0a69bf2c9c819255c7566e4355536d81d9cf, 77d059519382bd66283e6a4e83ee186e87e7708f, or f0729

Evidence notes

Vulnerability description confirms missing brelse() call in ext4_xattr_inode_dec_ref_all(). Source references indicate fixes applied to multiple stable kernel branches. No CVSS score or severity assigned by NVD at time of disclosure.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46046 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46046

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46046 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46046

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/097227f1ffe1a85bc3c359f81c71e3d40e06e920

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/1bc1107a3a403a6d440673ed6666f7b07ef868a8

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/1e6b0a69bf2c9c819255c7566e4355536d81d9cf

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/77d059519382bd66283e6a4e83ee186e87e7708f

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/f072906688933bf47fabbaf63560be03357c8298

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.