Security readout for executives and security teams
Plain-English summary
Samsung fixed a TelephonyUI access-control flaw in its May 2021 security maintenance release. On affected Samsung Mobile Devices running Android 9, 10, or 11, a malicious local app could write arbitrary files as the telephony process, risking device integrity and some service availability.
Executive priority
Treat this as a moderate mobile fleet hygiene issue, not an emergency based on the supplied evidence. Prioritize patch verification for Samsung devices that handle sensitive communications or are allowed to install unmanaged apps.
Technical view
CVE-2021-25397 is CWE-926 improper access control in TelephonyUI before SMR MAY-2021 Release 1. The CVSS 3.1 vector is AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L, meaning local attack, low complexity, no privileges, no user interaction, high integrity impact, and low availability impact.
Likely exposure
Exposure is most relevant to unmanaged or slow-patched Samsung Mobile Devices on Android P, Q, or R that predate Samsung SMR MAY-2021 Release 1. Enterprise risk depends on device inventory, patch level visibility, and exposure to untrusted app installation.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. The described attacker is local and can act through an untrusted application, so the practical scenario is malicious app presence on an affected Samsung device.
Researcher notes
The source bundle attributes arbitrary telephony-process file write to improper TelephonyUI access control before Samsung’s May 2021 release. Public evidence supplied here is sufficient for affected platform and patch direction, but not for model-specific impact, exploit maturity, or in-the-wild activity.
Mitigation direction
- Update affected Samsung devices to SMR MAY-2021 Release 1 or later.
- Prioritize corporate-managed Samsung devices running Android 9, 10, or 11.
- Restrict untrusted app installation through MDM or enterprise app controls.
- Review Samsung’s advisory for device-specific patch availability and status.
- Retire or isolate devices that cannot receive the May 2021 security maintenance release.
Validation and detection
- Inventory Samsung Mobile Devices and record Android version and security patch level.
- Flag Android 9, 10, or 11 devices below SMR MAY-2021 Release 1.
- Confirm TelephonyUI-related Samsung security updates are applied where available.
- Check MDM controls limiting sideloading and untrusted application sources.
- Document unsupported devices requiring compensating controls or replacement.
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
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Open ATT&CK lookupCVE-2021-25397 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
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:N/UI:N/S:U/C:N/I:H/A:L2.54.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.8MediumVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://blog.oversecured.com/Two-weeks-of-securing-Samsung-devices-Part-1/CVE reference · x_refsource_MISC
- https://security.samsungmobile.com/securityUpdate.smsb?year=2021&month=5CVE reference · x_refsource_MISC
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.
Improper Export of Android Application Components
Improper Export of Android Application Components represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.