CVE-2021-21042 | Acrobat Reader DC Out-Of-Bounds Read Information Disclosure Vulnerability

Acrobat Reader DC versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by an Out-of-bounds Read vulnerability that could lead to arbitrary disclosure of information in the memory stack. An attacker could leverage this vulnerability to bypass mitigations such as ASLR. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Published: 2021-02-11 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21042 is rated Moderate Risk (54.7/100): CVSS Medium severity, with high exploitation likelihood (EPSS 14.70%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-21042

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 44.97% 14.70% -30.26%
2 2025-07-08 38.37% 44.97% +6.59%
3 2025-07-07 — 38.37% —

Full EPSS history (45 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21042

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
6.5 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-21042

Affected software / configurations for CVE-2021-21042

Vendor Product Version Raw CPE
adobe acrobat >= 17.0, <= 17.011.30188 cpe:2.3:a:adobe:acrobat:*:*:*:*:classic:*:*:*
adobe acrobat >= 20.0, <= 20.001.30018 cpe:2.3:a:adobe:acrobat:*:*:*:*:classic:*:*:*
adobe acrobat_dc <= 20.013.20074 cpe:2.3:a:adobe:acrobat_dc:*:*:*:*:continuous:*:*:*
adobe acrobat_reader >= 17.0, <= 17.011.30188 cpe:2.3:a:adobe:acrobat_reader:*:*:*:*:classic:*:*:*
adobe acrobat_reader >= 20.0, <= 20.001.300183 cpe:2.3:a:adobe:acrobat_reader:*:*:*:*:classic:*:*:*
adobe acrobat_reader_dc <= 20.013.20074 cpe:2.3:a:adobe:acrobat_reader_dc:*:*:*:*:continuous:*:*:*

References for CVE-2021-21042

cvelogic Threat Intelligence