CVE-2021-33815Network attack vector

Information disclosure via unchecked EXR coefficient count

Published Jun 3, 2021 · Updated Aug 3, 2024

Out-of-bounds array access in FFmpeg 4.4 allows remote attackers to read unintended memory through a crafted OpenEXR image. In libavcodec/exr.c, dwa_uncompress accepts a dc_count below a loose maximum and uses it to size DC coefficient storage instead of requiring the image-derived dc_w * dc_h * 3 count. Opening or processing the image is required; the documented consequence is information disclosure, and public sources do not establish code execution.

CVSS severity8.8
High
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds array access in FFmpeg 4.4 allows remote attackers to read unintended memory through a crafted OpenEXR image. In libavcodec/exr.c, dwa_uncompress accepts a dc_count below a loose maximum and uses it to size DC coefficient storage instead of requiring the image-derived dc_w * dc_h * 3 count. Opening or processing the image is required; the documented consequence is information disclosure, and public sources do not establish code execution.

The record

CVE
CVE-2021-33815
Published
Jun 3, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-129
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 3, 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?

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 NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV: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 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-129Improper Validation of Array Index

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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