CVE-2021-31440
A public proof of concept exists; no exploitation attested.
- Published2021-05-21
- Fixed in5.12.4 · 5.11.21 · 5.10.37
- WeaknessCWE-682
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.11.15. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs prior to executing them. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. Was ZDI-CAN-13661.
Timeline
dates in UTC- 2021-05-2115:15CVE publishedNVD
- 2026-10-2319:23First public proof of conceptPoC-in-GitHub
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-31440?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-31440?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 5.12 | ≥ 5.12, < 5.12.4 | 5.12.4 | NVD |
| 5.11 | ≥ 5.11, < 5.11.21 | 5.11.21 | NVD |
| 5.x | ≥ 5.7, < 5.10.37 | 5.10.37 | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| — | all versions | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| — | all versions | no fix published | NVD |
7 more products in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
- Update Linux linux kernel to 5.12.4 · 5.11.21 · 5.10.37
Advisories and patches
- git.kernel.orgPatch · Vendor Advisory
Detection
read 2026-10-23 19:23 UTC- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
Sources
- NVDCVSS 3.17read 2026-10-23
- CNACVSS 3.08.8read 2026-10-23
- NVDCVSS 2.06.9read 2026-10-23
- CNAweakness (CWE)CWE-682read 2026-10-23
- FIRST EPSSEPSS score1.8 %2026-10-22
- PoC-in-GitHubproof of concept1read 2026-10-23
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Published
- 2021-05-21
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-31440?
Is CVE-2021-31440 actively exploited?
What is the CVSS score for CVE-2021-31440?
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