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CVE-2021-21017

Adobe — Adobe Acrobat and Reader Heap-based Buffer Overflow Vulnerability

Adobe · CWE-122 | CWE-787 — Out-of-bounds write · in CISA KEV since 2021-11-03

KEV since 2021 · listed over a yearCISA KEVActively Exploited
82

EVRS 82 of 100 Urgent

Patch This Cycle

Rank 545 of 2,960 tracked

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Why it scores 82

Evidence available: 6 of 7 signals

Listed in the CISA KEV catalog, and an EPSS probability of 0.863.

  • CISA KEVApplied
  • RansomwareDid not apply
  • Vendor exploitationDid not apply
  • EPSSApplied
  • Microsoft Exploitability IndexNot applicable
  • Pre-patch disclosureNo data
  • KEV recencyDid not apply
  • CVSSApplied

The band answers “how soon”, not “how bad”. No data for: Pre-patch disclosure. Why some signals show no data

Fix

Patch or fixed version identified

CISA required action

Fixed in

acrobat: update to a version newer than 17.011.30188 | acrobat: update to a version newer than 20.001.30018 | acrobat dc: update to a version newer than 20.013.20074 | acrobat reader: update to a version newer than 17.011.30188 | acrobat reader: update to a version newer than 20.001.300183 | acrobat reader dc: update to a version newer than 20.013.20074

Affected versions

  • acrobat>= 17.0 <= 17.011.30188>= 20.0 <= 20.001.30018
  • acrobat dc<= 20.013.20074
  • acrobat reader>= 17.0 <= 17.011.30188>= 20.0 <= 20.001.300183
  • acrobat reader dc<= 20.013.20074
  • macos
  • windows

Remediation

Apply updates per vendor instructions.

Fixed versions from NVD.

Evidence

Each value with its source
MeasureValueSource
CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. 8.8 NVD
FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. 0.863 (99.74th pctl) FIRST EPSS
Actively exploitedWhether a source of record has confirmed attacks using it in the wild. Confirmed CISA KEV
Ransomware campaign useWhether CISA has seen ransomware operators use it. Unknown or none CISA KEV
CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. 2021-11-17 · KEV since 2021 · listed over a year CISA KEV
Public exploit moduleA module existing is not the same as active exploitation. None known Metasploit
EUVD cross-referenceENISA's record: CVSS 8.8 (v3.1), assigned by adobe. Listed ENISA EUVD

Description

NVD

Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by a heap-based buffer overflow vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

What CISA says to do