CVE-2020-21598Public exploitNetwork attack vector

Memory corruption via SSE prediction heap overwrite

Published Sep 16, 2021 · Updated Aug 4, 2024

Heap buffer overflow in libde265 1.0.4 allows remote attackers to corrupt memory through a crafted HEVC file opened for decoding. The ff_hevc_put_unweighted_pred_8_sse routine writes a four-byte prediction value beyond its heap destination while processing malformed prediction data. A user must open or otherwise decode the file; the demonstrated consequence is a decoder abort, while process-memory corruption is inherent to the overwrite.

CVSS severity8.8
High
EPSS probability1.81%
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 libde265 1.0.4 allows remote attackers to corrupt memory through a crafted HEVC file opened for decoding. The ff_hevc_put_unweighted_pred_8_sse routine writes a four-byte prediction value beyond its heap destination while processing malformed prediction data. A user must open or otherwise decode the file; the demonstrated consequence is a decoder abort, while process-memory corruption is inherent to the overwrite.

The record

CVE
CVE-2020-21598
Published
Sep 16, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1203, T1204.002
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

8.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:P/I:P/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.

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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
T1203Exploitation for Client Execution
T1204.002Malicious File

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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