dbcve.org
AndroidOperating system · Google

CVE-2021-39627

HIGH · 7.8 CVSS v3.1 Published 2022-01-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In sendLegacyVoicemailNotification of LegacyModeSmsHandler.java, there is a possible permissions bypass due to an unsafe PendingIntent. This could lead to local escalation of privilege with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-9Android ID: A-185126549

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Android's LegacyModeSmsHandler.java, the sendLegacyVoicemailNotification method uses an unsafe PendingIntent that could allow a local attacker to perform privilege escalation by manipulating the mutable intent flags, bypassing normal permission checks.

MitigationApply the vendor-provided Android security patch (SVE-2021-185126549) which includes the fix for unsafe PendingIntent. Ensure PendingIntent uses FLAG_IMMUTABLE flag and proper intent handling in the affected code.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AndroidOperating system
Affected:= 9.0= 10.0= 11.0= 12.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Android OS version
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB
    Affected if The version is 9.0, 10.0, 11.0, or 12.0 exactly (not patched)
  2. Check security patch level
    Go to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' via ADB
    Affected if The security patch level is earlier than the SVE-2021-185126549 patch date (December 2021 or earlier for affected versions)
  3. Identify if LegacyModeSmsHandler component is present
    Check for the presence of framework.jar and inspect LegacyModeSmsHandler.java in the Android framework source code, or use a decompiler on the framework.jar from /system/framework/
    Affected if The vulnerable sendLegacyVoicemailNotification method exists and uses PendingIntent without FLAG_IMMUTABLE
  4. Verify PendingIntent flag usage in vulnerable method
    Review the source code of sendLegacyVoicemailNotification in LegacyModeSmsHandler.java for PendingIntent creation - look for getService or getBroadcast calls without FLAG_IMMUTABLE or FLAG_MUTABLE_UNCLEAR
    Affected if PendingIntent is created with mutable flags or no explicit immutability flag, allowing intent manipulation
  5. Confirm voicemail/SMS feature is enabled
    Check if the device uses legacy SMS/voicemail functionality - this is typically enabled by default on affected Android versions with carrier voicemail
    Affected if The device has SMS/voicemail capability and the LegacyModeSmsHandler code path can be triggered by a local app

A device is affected if it runs Android 9.0, 10.0, 11.0, or 12.0 without the SVE-2021-185126549 security patch and contains the vulnerable LegacyModeSmsHandler code with unsafe PendingIntent flags.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided Android security patch (SVE-2021-185126549) which includes the fix for unsafe PendingIntent. Ensure PendingIntent uses FLAG_IMMUTABLE flag and proper intent handling in the affected code.

Recommended fix High confidence

Update to Android security patch level January 2022 or later (Android 12, 12L, 11, 10, or 9 with January 2022 patch)

  1. Go to Settings on the Android device
  2. Navigate to System > Security (or Settings > Security & Location on some devices)
  3. Check for and install the latest system update
  4. Ensure the installed security patch level is January 2022 or later

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39627 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data