CVE-2021-0993Network attack vector

Remote service interruption via empty text runs

Published Dec 15, 2021 · Updated Aug 3, 2024

Resource-exhaustion denial of service in Android 12 TextLine allows remote attackers to interrupt a device through crafted styled text. TextLine.getOffsetBeforeAfter fails to bypass span lookup when a bidirectional text run has an empty target region, allowing repeated processing to exhaust resources. Exploitation requires no privileges but requires a user to interact with attacker-supplied content; only device availability is affected.

CVSS severity6.5
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource-exhaustion denial of service in Android 12 TextLine allows remote attackers to interrupt a device through crafted styled text. TextLine.getOffsetBeforeAfter fails to bypass span lookup when a bidirectional text run has an empty target region, allowing repeated processing to exhaust resources. Exploitation requires no privileges but requires a user to interact with attacker-supplied content; only device availability is affected.

The record

CVE
CVE-2021-0993
Published
Dec 15, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Android
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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-12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Androidversion=Android-12

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

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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