ext4: fix mb_cache_entry's e_refcnt leak in ext4_xattr_block_cache_find()
Priority LOW 24Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 14 fixed, 2 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00231 14th percentileScored 2026-11-07
Fix Partial Linux (Linux): 4.19.316, 4.15, 4.21 +7Red Hat: 4 advisoriesRed Hat: 14 fixed, 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.19.14 to before 4.19.316; 4.14.92 to before 4.15; 4.20.1 to before 4.21 | 4.19.316, 4.15, 4.21 | Patch available | CNA |
| Linux | Linux | 5.0 and later | 4.19.316, 5.4.278, 5.10.219, 5.15.161, 6.1.94, 6.6.34, 6.9.5, 6.10 | Patch available | CNA |
- Linux VendorLinux Affected 4.19.14 to before 4.19.316; 4.14.92 to before 4.15; 4.20.1 to before 4.21 Fixed in 4.19.316, 4.15, 4.21 Patch available CNA
- Linux VendorLinux Affected 5.0 and later Fixed in 4.19.316, 5.4.278, 5.10.219, 5.15.161, 6.1.94, 6.6.34, 6.9.5, 6.10 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 4.14.92 to before 4.15; 4.19.14 to before 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 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 4.14.92 to before 4.15; 4.19.14 to before 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 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.19.316, 4.15, 4.21
- Fix · CNA Linux (Linux) Fixed in 4.19.316, 5.4.278, 5.10.219, 5.15.161, 6.1.94, 6.6.34, 6.9.5, 6.10
Red Hat 4 advisories
- RHSA-2025:2270 Released 2025-03-05 · Red Hat rating Moderatekernel security update
- Red Hat CodeReady Linux Builder EUS (v.9.4) kernel-tools-libs-devel-5.14.0-427.57.1.el9_4, libperf-5.14.0-427.57.1.el9_4
- Red Hat Enterprise Linux AppStream EUS (v.9.4) kernel-64k-debug-devel-5.14.0-427.57.1.el9_4, kernel-64k-debug-devel-matched-5.14.0-427.57.1.el9_4, kernel-64k-devel-5.14.0-427.57.1.el9_4 +11
- Red Hat Enterprise Linux BaseOS EUS (v.9.4) bpftool-7.3.0-427.57.1.el9_4, kernel-5.14.0-427.57.1.el9_4, kernel-64k-5.14.0-427.57.1.el9_4 +29
- Red Hat Enterprise Linux Real Time EUS (v.9.4) kernel-rt-5.14.0-427.57.1.el9_4, kernel-rt-core-5.14.0-427.57.1.el9_4, kernel-rt-debug-5.14.0-427.57.1.el9_4 +9
- Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt-5.14.0-427.57.1.el9_4, kernel-rt-core-5.14.0-427.57.1.el9_4, kernel-rt-debug-5.14.0-427.57.1.el9_4 +11
- RHSA-2024:9315 Released 2024-11-12 · Red Hat rating Moderatekernel security update
- Red Hat CodeReady Linux Builder (v. 9) kernel-cross-headers-5.14.0-503.11.1.el9_5, kernel-tools-libs-devel-5.14.0-503.11.1.el9_5, libperf-5.14.0-503.11.1.el9_5
- Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-503.11.1.el9_5, kernel-64k-debug-devel-matched-5.14.0-503.11.1.el9_5, kernel-64k-devel-5.14.0-503.11.1.el9_5 +12
- Red Hat Enterprise Linux BaseOS (v. 9) bpftool-7.4.0-503.11.1.el9_5, kernel-5.14.0-503.11.1.el9_5, kernel-64k-5.14.0-503.11.1.el9_5 +30
- Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-503.11.1.el9_5, kernel-rt-core-5.14.0-503.11.1.el9_5, kernel-rt-debug-5.14.0-503.11.1.el9_5 +9
- Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-503.11.1.el9_5, kernel-rt-core-5.14.0-503.11.1.el9_5, kernel-rt-debug-5.14.0-503.11.1.el9_5 +11
- RHSA-2024:5101 Released 2024-08-08 · Red Hat rating Importantkernel security update
- Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.16.1.el8_10, kernel-4.18.0-553.16.1.el8_10, kernel-abi-stablelists-4.18.0-553.16.1.el8_10 +19
- Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.16.1.el8_10
Show 1 more Red Hat advisories
- RHSA-2024:5102 Released 2024-08-08 · Red Hat rating Importantkernel-rt security update
- Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-4.18.0-553.16.1.rt7.357.el8_10 +9
- Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core-4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-4.18.0-553.16.1.rt7.357.el8_10 +7
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat CodeReady Linux Builder (v. 9) | Fixed | RHSA-2024:9315 |
| Red Hat CodeReady Linux Builder EUS (v.9.4) | Fixed | RHSA-2025:2270 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2024:9315 |
| Red Hat Enterprise Linux AppStream EUS (v.9.4) | Fixed | RHSA-2025:2270 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2024:5101 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2024:9315 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.4) | Fixed | RHSA-2025:2270 |
| Red Hat Enterprise Linux CRB (v. 8) | Fixed | RHSA-2024:5101 |
| Red Hat Enterprise Linux NFV (v. 8) | Fixed | RHSA-2024:5102 |
| Red Hat Enterprise Linux RT (v. 8) | Fixed | RHSA-2024:5102 |
| Red Hat Enterprise Linux Real Time (v. 9) | Fixed | RHSA-2024:9315 |
| Red Hat Enterprise Linux Real Time EUS (v.9.4) | Fixed | RHSA-2025:2270 |
| Red Hat Enterprise Linux Real Time for NFV (v. 9) | Fixed | RHSA-2024:9315 |
| Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) | Fixed | RHSA-2025:2270 |
Not affected: 2 products
- Red Hat CodeReady Linux Builder (v. 9)
- Red Hat Enterprise Linux AppStream (v. 9)
Timeline
- 2026-10-02 Threatist record created from CVE-2024-39276
- 2026-10-03 Alias added: GHSA-hf2g-j6wm-qrrx
- 2026-10-29 Affected versions changed · Red Hat
References
Patch 8
- https://git.kernel.org/stable/c/9ad75e78747b5a50dc5a52f0f8e92e920a653f16
- https://git.kernel.org/stable/c/896a7e7d0d555ad8b2b46af0c2fa7de7467f9483
- https://git.kernel.org/stable/c/76dc776153a47372719d664e0fc50d6355791abb
- https://git.kernel.org/stable/c/681ff9a09accd8a4379f8bd30b7a1641ee19bb3e
- https://git.kernel.org/stable/c/e941b712e758f615d311946bf98216e79145ccd9
- https://git.kernel.org/stable/c/a95df6f04f2c37291adf26a74205cde0314d4577
- https://git.kernel.org/stable/c/b37c0edef4e66fb21a2fbc211471195a383e5ab8
- https://git.kernel.org/stable/c/0c0b4a49d3e7f49690a6827a41faeffad5df7e21
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- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2024-39276 · CVE Program
- CVE-2024-39276 · NVD
- FIRST EPSS
- GHSA-hf2g-j6wm-qrrx · GitHub Advisory Database · CC BY 4.0
- CVE-2024-39276 · Red Hat security data · CC BY 4.0
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