Security readout for executives and security teams
Plain-English summary
This Android flaw could let a local app become the default contactless payment app without the user approving the change. That creates business risk around unauthorized payment handling and device trust. Sources do not show confirmed active exploitation.
Executive priority
Treat this as high priority for Android 13 fleets using contactless payments. The issue affects user consent and payment trust, but current sources do not prove active exploitation.
Technical view
CVE-2021-39810 is a missing permission check in Android CardEmulationManager.java verifyDefaults. A low-privileged local actor could set a third-party app as the default contactless payment app without user interaction. CVSS 3.1 is 7.8 high, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is indicated for Google Android 13. Organizations with Android 13 devices, especially unmanaged or BYOD devices using NFC payments, should verify OEM security patch status against the Android bulletin.
Exploitation context
The CVE describes local privilege escalation requiring low privileges and no user interaction. The provided data marks KEV as false and gives no source confirming exploitation in the wild.
Researcher notes
Evidence is limited to the CVE record and Android bulletin references. The core weakness is CWE-862, missing authorization. Do not assume Android versions beyond Android 13 are affected unless vendor documentation confirms it.
Mitigation direction
- Check Google and OEM guidance for CVE-2021-39810 updates.
- Prioritize Android 13 devices for relevant security updates.
- Use MDM to restrict untrusted app installation where possible.
- Review NFC payment app policy and approved payment applications.
- Track OEM patch availability for all managed Android models.
Validation and detection
- Inventory Android 13 devices across managed and BYOD fleets.
- Compare device security patch levels with vendor bulletin guidance.
- Review default contactless payment app settings for unexpected changes.
- Check installed apps for unapproved payment or NFC handlers.
- Confirm MDM policies enforce approved payment app configuration.
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-862: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. 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-2021-39810 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
- No
- 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.
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/2025-09-01CVE reference
- https://source.android.com/docs/security/bulletin/android-14CVE reference · x_transferred
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.
Missing Authorization
Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.