CVE-2021-39826

Arbitrary command execution via crafted EPUB file

Published Sep 27, 2021 · Updated Sep 17, 2024

OS command injection in Adobe Digital Editions 4.5.11.187646 and earlier allows context-dependent attackers to execute arbitrary commands. Adobe identifies crafted EPUB processing as the trigger but has not disclosed the affected parser or how file content reaches an operating-system command. A user must open the malicious EPUB on macOS; successful exploitation runs arbitrary commands in the application's security context.

CVSS severity8.6
High
EPSS probability2.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Adobe Digital Editions 4.5.11.187646 and earlier allows context-dependent attackers to execute arbitrary commands. Adobe identifies crafted EPUB processing as the trigger but has not disclosed the affected parser or how file content reaches an operating-system command. A user must open the malicious EPUB on macOS; successful exploitation runs arbitrary commands in the application's security context.

The record

CVE
CVE-2021-39826
Published
Sep 27, 2021
Updated
Sep 17, 2024
Vendor
Adobe
Product
Adobe Digital Editions
Classifications
CWE-78, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=unspecified <=4.5.11.187646
  2. Affected versionversion=unspecified <=None

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Adobe · Adobe Digital Editionsversion=unspecified <=4.5.11.187646; version=unspecified <=None

Published CVSS scores

9.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:C/I:C/A:C
8.6Adobe Systems IncorporatedCVSS: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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1204.002Malicious File

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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