CVE-2021-44957Public exploitNetwork attack vector

Codec crash via oversized Huffman table copy

Published Feb 8, 2022 · Updated Aug 4, 2024

Global buffer overflow in ffjpeg through 01.01.2021 allows context-dependent attackers to crash the codec with a crafted image file. jfif_encode copies 272 bytes from the 178-byte STD_HUFTAB_LUMIN_AC global table, causing an out-of-bounds read in memcpy. A victim must direct ffjpeg to encode the crafted input; the read aborts the process without reported data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Global buffer overflow in ffjpeg through 01.01.2021 allows context-dependent attackers to crash the codec with a crafted image file. jfif_encode copies 272 bytes from the 178-byte STD_HUFTAB_LUMIN_AC global table, causing an out-of-bounds read in memcpy. A victim must direct ffjpeg to encode the crafted input; the read aborts the process without reported data disclosure or modification.

The record

CVE
CVE-2021-44957
Published
Feb 8, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499.004, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 8, 2022CVE 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

6.5NIST 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 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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Endpoint Denial of Service: Application or System Exploitation
T1204.002User Execution: Malicious 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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