Security readout for executives and security teams
Plain-English summary
CVE-2021-39793 is an Android kernel flaw that can let a local attacker raise privileges on an affected device. It does not require user interaction, but it does require local low-privileged access. CISA lists it in KEV, so treat it as exploited in the wild.
Executive priority
Prioritize remediation for managed Android fleets because CISA KEV indicates real-world exploitation. The issue is local rather than remote, so urgency is highest for exposed, shared, high-value, or poorly managed devices.
Technical view
The issue is a CWE-787 out-of-bounds write in kbase_jd_user_buf_pin_pages in mali_kbase_mem.c. The CVSS 3.1 vector is local, low complexity, low privileges required, no user interaction, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most relevant to Android devices whose kernel includes the vulnerable Mali kbase code and that have not received the relevant Android, Pixel, OEM, or carrier security update covering CVE-2021-39793.
Exploitation context
CISA KEV coverage supports known exploitation. The public CVE description indicates local privilege escalation, not remote exploitation. The provided sources do not include exploit details, affected device models beyond Android kernel, or a standalone mitigation.
Researcher notes
Evidence supports an Android kernel local privilege escalation through an out-of-bounds write in Mali kbase memory handling. The source bundle does not provide exploit mechanics, model-level scope, commit details, or detailed remediation beyond referenced security bulletins.
Mitigation direction
- Apply Android, Pixel, OEM, or carrier updates covering CVE-2021-39793.
- Prioritize managed Android devices used by privileged or high-risk users.
- Check vendor guidance where patch mapping is unclear.
- Retire or isolate devices that cannot receive kernel security updates.
Validation and detection
- Inventory Android devices and record kernel and security patch levels.
- Confirm vendor bulletins map installed updates to CVE-2021-39793.
- Use MDM reporting to verify update compliance across the fleet.
- Track exceptions for unsupported or delayed-update devices.
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-787: 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 lookupCVE-2021-39793 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
- 7.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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.
CISA KEV status
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:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://source.android.com/security/bulletin/pixel/2022-03-01CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-39793CVE reference · government-resource
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.