CVE-2021-28021Public exploit

Application crash via malformed JPEG DC delta

Published Oct 15, 2021 · Updated Aug 3, 2024

Out-of-bounds read in stb_image 2.26 allows context-dependent attackers to crash applications through a crafted JPEG file. The JPEG Huffman decoder accepts an out-of-range DC delta bit count and passes it to stbi__extend_receive, which indexes beyond the 64-byte stbi__jbias table. A victim application must process the malicious image; the published proof of concept demonstrates an AddressSanitizer-detected abort, while confidentiality effects remain context dependent.

CVSS severity7.8
High
EPSS probability1.43%
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 read in stb_image 2.26 allows context-dependent attackers to crash applications through a crafted JPEG file. The JPEG Huffman decoder accepts an out-of-range DC delta bit count and passes it to stbi__extend_receive, which indexes beyond the 64-byte stbi__jbias table. A victim application must process the malicious image; the published proof of concept demonstrates an AddressSanitizer-detected abort, while confidentiality effects remain context dependent.

The record

CVE
CVE-2021-28021
Published
Oct 15, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 15, 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 vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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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