CVE-2021-0690Network attack vector

Information disclosure via unchecked slice counter increment

Published Oct 6, 2021 · Updated Aug 3, 2024

Heap buffer overflow in Android Media Codecs 8.1 through 11 allows remote attackers to disclose information through crafted H.264 media. The libavc decoder increments u2_cur_slice_num even when the current slice has no macroblock memory left, allowing ih264d_mark_err_slice_skip to write past heap bounds. Exploitation requires a user to process attacker-controlled media; no execution privileges are needed, and the documented consequence is information disclosure.

CVSS severity6.5
Medium
EPSS probability0.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in Android Media Codecs 8.1 through 11 allows remote attackers to disclose information through crafted H.264 media. The libavc decoder increments u2_cur_slice_num even when the current slice has no macroblock memory left, allowing ih264d_mark_err_slice_skip to write past heap bounds. Exploitation requires a user to process attacker-controlled media; no execution privileges are needed, and the documented consequence is information disclosure.

The record

CVE
CVE-2021-0690
Published
Oct 6, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 6, 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-9 Android-10 Android-11 Android-8.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Androidversion=Android-9 Android-10 Android-11 Android-8.1

Published CVSS scores

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

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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