CVE-2021-30354Public exploit

Code execution via JBIG2 image-size integer overflow

Published Sep 1, 2021 · Updated Aug 3, 2024

Memory corruption in the PDF parser in Amazon Kindle Firmware 5.13.4 and earlier allows attackers to execute code when a crafted PDF book is opened. CJBig2Image::expand() calculates a resized JBIG2 image allocation without checking INT_MAX, so a 32-bit wrap creates a small heap buffer before refinement data is written beyond it. Opening the malicious book is required, and successful exploitation runs code with the Kindle framework user's privileges.

CVSS severity8.6
High
EPSS probability8.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the PDF parser in Amazon Kindle Firmware 5.13.4 and earlier allows attackers to execute code when a crafted PDF book is opened. CJBig2Image::expand() calculates a resized JBIG2 image allocation without checking INT_MAX, so a 32-bit wrap creates a small heap buffer before refinement data is written beyond it. Opening the malicious book is required, and successful exploitation runs code with the Kindle framework user's privileges.

The record

CVE
CVE-2021-30354
Published
Sep 1, 2021
Updated
Aug 3, 2024
Vendor
Amazon
Product
Kindle Firmware
Classifications
CWE-680, CWE-190, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 1, 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=All versions prior to and including 5.13.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Amazon · Kindle Firmwareversion=All versions prior to and including 5.13.4

Published CVSS scores

9.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:C/I:C/A:C
8.6NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/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-680Integer Overflow to Buffer Overflow
CWE-190Integer Overflow or Wraparound
T1203Exploitation for Client Execution

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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