CVE-2021-39659

Emergency-call denial via PhoneAccount sorting overflow

Published Jan 14, 2022 · Updated Aug 4, 2024

Denial of service in Google Cloud Android 10 through 12 allows local users to prevent emergency calls through a Telecom exception. CreateConnectionProcessor.sortSimPhoneAccountsForEmergency subtracts PhoneAccount hash codes while sorting duplicate accounts, allowing integer overflow or underflow to produce an invalid comparison and an unhandled exception. User-level execution can establish the duplicate-account condition, no user interaction is required, and the bounded consequence is interruption of emergency-call placement.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Google Cloud Android 10 through 12 allows local users to prevent emergency calls through a Telecom exception. CreateConnectionProcessor.sortSimPhoneAccountsForEmergency subtracts PhoneAccount hash codes while sorting duplicate accounts, allowing integer overflow or underflow to produce an invalid comparison and an unhandled exception. User-level execution can establish the duplicate-account condition, no user interaction is required, and the bounded consequence is interruption of emergency-call placement.

The record

CVE
CVE-2021-39659
Published
Jan 14, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-755, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Android-10 Android-11 Android-12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android-10 Android-11 Android-12

Published CVSS scores

4.7NIST NVDAV:L/AC:M/Au:N/C:N/I:N/A:C
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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