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Linux KernelOperating system · Linux

CVE-2024-39276

MEDIUM · 5.5 CVSS v3.1 Published 2024-06-25
Fix available
A fix is available. Upgrade to 4.15 / 4.19.316 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ext4: fix mb_cache_entry's e_refcnt leak in ext4_xattr_block_cache_find() Syzbot reports a warning as follows: ============================================ WARNING: CPU: 0 PID: 5075 at fs/mbcache.c:419 mb_cache_destroy+0x224/0x290 Modules linked in: CPU: 0 PID: 5075 Comm: syz-executor199 Not tainted 6.9.0-rc6-gb947cc5bf6d7 RIP: 0010:mb_cache_destroy+0x224/0x290 fs/mbcache.c:419 Call Trace: <TASK> ext4_put_super+0x6d4/0xcd0 fs/ext4/super.c:1375 generic_shutdown_super+0x136/0x2d0 fs/super.c:641 kill_block_super+0x44/0x90 fs/super.c:1675 ext4_kill_sb+0x68/0xa0 fs/ext4/super.c:7327 [...] ============================================ This is because when finding an entry in ext4_xattr_block_cache_find(), if ext4_sb_bread() returns -ENOMEM, the ce's e_refcnt, which has already grown in the __entry_find(), won't be put away, and eventually trigger the above issue in mb_cache_destroy() due to reference count leakage. So call mb_cache_entry_put() on the -ENOMEM error branch as a quick fix.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 4.14.92, < 4.15>= 4.19.14, < 4.19.316>= 4.20.1, <= 5.4.278>= 5.5, <= 5.15.161>= 5.16, <= 6.1.94>= 6.2, <= 6.6.34>= 6.7, <= 6.9.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.15 / 4.19.316 or later
Fixed in 4.154.19.316
Vendor patch git.kernel.org →
Recommended fix High confidence

4.19.316+ / 5.4.279+ / 5.15.162+ (depending on branch)

  1. Identify your current kernel version using `uname -r`
  2. Determine which version branch you are on from the affected ranges: 4.14.x, 4.19.x, 5.4.x, or 5.15.x
  3. For 4.19.x: upgrade to kernel version 4.19.316 or later
  4. For 5.4.x: upgrade to kernel version 5.4.279 or later
  5. For 5.15.x: upgrade to kernel version 5.15.162 or later
  6. For 4.14.x: the 4.15 release is affected and the fix is not available in that branch; migrate to a supported stable branch like 5.4 or 5.15
  7. Reboot the system to load the fixed kernel
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with custom modules or older drivers; test in staging first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-39276 in production — separate from our analysis above.

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