Security readout for executives and security teams
Plain-English summary
CVE-2021-34981 is a Linux kernel Bluetooth CMTP module double-free flaw. A local attacker who already has high-privileged code execution could potentially gain kernel-level execution. Business urgency is highest for Linux systems exposing Bluetooth/CMTP functionality and allowing privileged local workloads or administrators.
Executive priority
Treat as a targeted Linux hardening and patch-management issue, not a broad internet-exposed emergency. Prioritize affected Linux hosts that allow privileged local users, run shared workloads, or enable Bluetooth functionality. Require vendor confirmation before assuming scope beyond the cited kernel version.
Technical view
The flaw is in the Linux kernel CMTP module and is classified as CWE-415 double free. The issue comes from failing to validate an object’s existence before additional free operations. The cited affected version is Linux Kernel 4.15.0-118-generic; broader affected status is not established in the provided sources.
Likely exposure
Likely exposure is narrow: Linux systems using the affected kernel build and CMTP Bluetooth functionality. The source bundle identifies Linux Kernel 4.15.0-118-generic only and marks default affected status as unknown, so organizations should validate through their Linux vendor and asset inventory.
Exploitation context
No active exploitation is supported by the provided sources, and this CVE is not marked as CISA KEV in the bundle. Exploitation requires local access and high privileges, with high attack complexity, but successful exploitation could execute code in the kernel context.
Researcher notes
Evidence supports a CMTP module double free with potential kernel-context execution, but the bundle does not provide patch details, exploit availability, or a complete affected-version matrix. Avoid broad claims until vendor advisories or kernel commit references confirm branch impact and fixed versions.
Mitigation direction
- Check Linux vendor advisories for affected kernel packages and fixes.
- Apply vendor-provided kernel updates where CVE-2021-34981 is addressed.
- Inventory systems running Linux Kernel 4.15.0-118-generic or vendor-equivalent packages.
- Restrict high-privileged local access on potentially affected Linux systems.
- If CMTP is unnecessary, consider vendor-supported Bluetooth/CMTP hardening controls.
Validation and detection
- Confirm kernel versions on Linux assets against vendor package advisories.
- Determine whether Bluetooth CMTP functionality is present or loaded on exposed systems.
- Review kernel changelogs for CVE-2021-34981 remediation references.
- Prioritize validation on systems with privileged local users or workloads.
- Track whether vendors list additional affected kernel branches.
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-415: 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-34981 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
- 7.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:H/PR:H/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:H/PR:H/UI:N/S:C/C:H/I:H/A:H0.86Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- ZDI-21-1223CVE reference · x_research-advisory
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.
Double Free
Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.