CVE-2021-35987

Memory disclosure via PDFLibTool out-of-bounds read

Published Aug 20, 2021 · Updated Sep 17, 2024

Out-of-bounds read in Adobe Acrobat Reader 2017, 2020, and DC allows attackers to disclose process memory through a malicious PDF. Adobe identifies PDFLibTool as the affected component but has not published which parsing operation reads beyond its buffer boundary. Exploitation requires a victim to open a malicious file, and the documented consequence is memory disclosure in the current user's context.

CVSS severity3.3
Low
EPSS probability2.14%
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 Adobe Acrobat Reader 2017, 2020, and DC allows attackers to disclose process memory through a malicious PDF. Adobe identifies PDFLibTool as the affected component but has not published which parsing operation reads beyond its buffer boundary. Exploitation requires a victim to open a malicious file, and the documented consequence is memory disclosure in the current user's context.

The record

CVE
CVE-2021-35987
Published
Aug 20, 2021
Updated
Sep 17, 2024
Vendor
Adobe
Product
Adobe Acrobat Reader
Classifications
CWE-125, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 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 <=2017.011.30197
  2. Affected versionversion=unspecified <=2020.004.30005
  3. Affected versionversion=unspecified <=2021.005.20054
  4. Affected versionversion=unspecified <=None

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Adobe · Adobe Acrobat Readerversion=unspecified <=2017.011.30197; version=unspecified <=2020.004.30005; version=unspecified <=2021.005.20054; version=unspecified <=None

Published CVSS scores

3.3AdobeCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
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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