mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path". Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race with their writes, results in use-after-free. Fix those. This patch (of 2): damon_sysfs_scheme_filter->mmecg_path can be read and written by users, via DAMON sysfs memcg_path file. It can also be indirectly read, for the parameters {on,off}line committing to DAMON. The reads for parameters committing are protected by damon_sysfs_lock to avoid the sysfs files being destroyed while any of the parameters are being read. But the user-driven direct reads and writes are not protected by any lock, while the write is deallocating the memcg_path-pointing buffer. As a result, the readers could read the already freed buffer (user-after-free). Note that the user-reads don't race when the same open file is used by the writer, due to kernfs's open file locking. Nonetheless, doing the reads and writes with separate open files would be common. Fix it by protecting both the user-direct reads and writes with damon_sysfs_lock.
Why it matters now
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 | 6.6.96 to before 6.6.140; 6.12.36 to before 6.12.88; 6.15.5 to before 6.16 | 6.6.140, 6.12.88, 6.16 | Patch available | CNA |
| Linux | Linux | 6.16 and later | 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 6.6.96 to before 6.6.140; 6.12.36 to before 6.12.88; 6.15.5 to before 6.16 Fixed in 6.6.140, 6.12.88, 6.16 Patch available CNA
- Linux VendorLinux Affected 6.16 and later Fixed in 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1 Patch available CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 6.6.96 to before 6.6.140; 6.12.36 to before 6.12.88; 6.15.5 to before 6.16; 6.16.1 to before 6.18.30; 6.19 to before 7.0.7 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.16:-:*:*:*:*:*:* | 6.16 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:* | 6.16 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:* | 6.16 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.16:rc6:*:*:*:*:*:* | 6.16 rc6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.16:rc7:*:*:*:*:*:* | 6.16 rc7 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | 7.1 rc1 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.6.96 to before 6.6.140; 6.12.36 to before 6.12.88; 6.15.5 to before 6.16; 6.16.1 to before 6.18.30; 6.19 to before 7.0.7 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.16:-:*:*:*:*:*:* Versions 6.16 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:* Versions 6.16 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:* Versions 6.16 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.16:rc6:*:*:*:*:*:* Versions 6.16 rc6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.16:rc7:*:*:*:*:*:* Versions 6.16 rc7 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* Versions 7.1 rc1 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.6.140, 6.12.88, 6.16
- Fix · CNA Linux (Linux) Fixed in 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-46121
- 2026-10-03 Alias added: GHSA-496c-fq9m-2rhq
- 2026-10-29 Affected versions changed · Red Hat
- 2026-11-06 CISA SSVC decision points changed
References
Patch 5
- https://git.kernel.org/stable/c/b1e9f2d5870776347edef927f9bb3ea19b8e3abb
- https://git.kernel.org/stable/c/c88802d0e8edd14b6cd2daf3000f99adbc4c85c5
- https://git.kernel.org/stable/c/eafd6f5372d29b0dd213799b92c2c9c7ad31d7da
- https://git.kernel.org/stable/c/baecc45ad60e621ef14d6c1e7f41ef36bbfdf910
- https://git.kernel.org/stable/c/1e68eb96e8beb1abefd12dd22c5637795d8a877e
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Sources
- CVE-2026-46121 · CVE Program
- CVE-2026-46121 · NVD
- FIRST EPSS
- GHSA-496c-fq9m-2rhq · GitHub Advisory Database · CC BY 4.0
- CVE-2026-46121 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences