CVE-2021-47461
userfaultfd: fix a race between writeprotect and exit_mmap()
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.
Timeline
ID reserved
By Linux
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Medium4.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.17% · top 93% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Weakness
Affected products
- affected 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 – < 3cda4bfffd4f755645577aaa9e96a606657b4525
- affected 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 – < 149958ecd0627a9f1e9c678c25c665400054cd6a
- affected 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 – < cb185d5f1ebf900f4ae3bf84cee212e6dd035aca
- affected 5.7
- unaffected < 5.7
- unaffected 5.10.76 – ≤ 5.10.*
- unaffected 5.14.15 – ≤ 5.14.*
- unaffected 5.15 – ≤ *
References (3)
- https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-47461)Record last updated .