Security readout for executives and security teams
Plain-English summary
CVE-2021-31440 is a local privilege escalation flaw in Linux Kernel 5.11.15. A person or workload that can already run low-privileged code on the system may be able to gain kernel-level control. Business risk is highest on shared Linux hosts, exposed shell environments, and systems running untrusted workloads.
Executive priority
Treat this as a high-priority patching issue for Linux systems that allow local code execution by users or workloads. It is not described as remotely exploitable in the sources, but successful exploitation could mean full system compromise.
Technical view
The flaw is in eBPF program handling and stems from insufficient validation of user-supplied eBPF programs before execution. The CVSS 3.0 score is 8.8, with local access, low complexity, low privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Confirmed exposure is Linux Kernel 5.11.15. Systems are most relevant where local users, services, build jobs, or workloads can execute code. Downstream vendor exposure depends on whether their kernels include the vulnerable code or a backported fix.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires prior ability to execute low-privileged code locally, then abuses eBPF validation weakness to escalate into kernel context.
Researcher notes
Focus validation on kernel lineage and eBPF handling, not only nominal version strings, because vendors may backport fixes. Evidence in the bundle identifies Linux Kernel 5.11.15 and an upstream commit reference, but does not provide broader affected-version ranges.
Mitigation direction
- Inventory Linux systems and identify any running kernel 5.11.15.
- Apply vendor or distribution kernel updates that include the upstream fix.
- Check appliance and platform vendor advisories, including NetApp guidance where relevant.
- Limit untrusted local code execution on unpatched shared Linux hosts.
- Prioritize patching systems with shell users, CI runners, or multi-tenant workloads.
Validation and detection
- Confirm each host kernel version after remediation.
- Verify vendor release notes reference CVE-2021-31440 or the upstream fix commit.
- Run authenticated vulnerability scanning for Linux kernel package state.
- Review exposure of local users, services, and scheduled jobs on unpatched hosts.
- Document exceptions and compensating controls for systems awaiting vendor fixes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-682: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31440 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H26Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.zerodayinitiative.com/advisories/ZDI-21-503/CVE reference · x_refsource_MISC
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=10bf4e83167cc68595b85fd73bb91e8f2c086e36CVE reference · x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210706-0003/CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Incorrect Calculation
Incorrect Calculation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.