CVE-2021-3496Public exploit

Process crash via unchecked Canon maker-note length

Published Apr 22, 2021 · Updated Aug 3, 2024

Heap-buffer over-read in Matthias Wandel Jhead 3.06 allows attackers to crash the command-line process with a crafted JPEG file. Canon maker-note parsing trusts the declared component count and calls Get16u past the allocated value buffer without first requiring enough bytes for the indexed field. Exploitation requires the crafted JPEG to be opened by Jhead; the demonstrated consequence is a process crash, and Debian reports no security impact beyond the CLI failure.

CVSS severity7.8
High
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 Matthias Wandel Jhead 3.06 allows attackers to crash the command-line process with a crafted JPEG file. Canon maker-note parsing trusts the declared component count and calls Get16u past the allocated value buffer without first requiring enough bytes for the indexed field. Exploitation requires the crafted JPEG to be opened by Jhead; the demonstrated consequence is a process crash, and Debian reports no security impact beyond the CLI failure.

The record

CVE
CVE-2021-3496
Published
Apr 22, 2021
Updated
Aug 3, 2024
Vendor
Matthias Wandel
Product
Jhead
Classifications
CWE-787, CWE-119, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=jhead 3.06.0.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Matthias Wandel · Jheadversion=jhead 3.06.0.1

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS: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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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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