CVE-2020-21604Public exploitNetwork attack vector

Application crash via out-of-bounds SIMD read

Published Sep 16, 2021 · Updated Aug 4, 2024

Heap-buffer over-read in libde265 1.0.4 allows attackers to crash applications that decode a crafted HEVC file. During chroma motion compensation, ff_hevc_put_hevc_epel_pixels_8_sse passes an out-of-range picture-buffer address to _mm_loadl_epi64, which reads eight bytes 80 bytes beyond the allocation. A victim must cause an application using the x86 SSE decoder path to process the crafted file; the published reproduction shows an AddressSanitizer abort, with no demonstrated code execution.

CVSS severity6.5
Medium
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-buffer over-read in libde265 1.0.4 allows attackers to crash applications that decode a crafted HEVC file. During chroma motion compensation, ff_hevc_put_hevc_epel_pixels_8_sse passes an out-of-range picture-buffer address to _mm_loadl_epi64, which reads eight bytes 80 bytes beyond the allocation. A victim must cause an application using the x86 SSE decoder path to process the crafted file; the published reproduction shows an AddressSanitizer abort, with no demonstrated code execution.

The record

CVE
CVE-2020-21604
Published
Sep 16, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 16, 2021CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002Malicious File
T1499.004Application or System Exploitation

Public exploit references

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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