Cyber Resilience

CVE-2021-28550

Memory Safety in Adobe Acrobat Dc 15.008.20082 – 21.001.20150

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
02 September 2021
Modified
23 October 2025
KEV Added
03 November 2021
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.52 99th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2021-28550 is a high-severity Use After Free (CWE-416) vulnerability in Adobe Acrobat Dc. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 1% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Acrobat Reader DC versions 2021.001.20150 and earlier, 2020.001.30020 and earlier, and 2017.011.30194 and earlier are affected by a Use After Free vulnerability (CWE-416) with a CVSS 3.1 score of 8.8. The flaw resides in the PDF handling components of these releases and can result in memory corruption when specially crafted content is processed.

An unauthenticated attacker can leverage the vulnerability for arbitrary code execution in the context of the current user. Successful exploitation requires the victim to open a malicious file, after which the attacker gains control within the reader's process.

Adobe security bulletin APSB21-29 addresses the issue and supplies updated builds that remediate the use-after-free condition. The vulnerability is also listed in CISA's catalog of known exploited vulnerabilities, confirming observed in-the-wild activity.

EU & UK References

Vulnerability Data

Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the…

more

current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

CWE(s)
CWE-416
KEV Date Added
03 November 2021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-21608Same product: Adobe Acrobatboth on KEV
CVE-2020-9715Same product: Adobe Acrobat Dcboth on KEV
CVE-2025-27159Same product: Adobe Acrobat
CVE-2023-44361Same product: Adobe Acrobat
CVE-2024-34100Same product: Adobe Acrobat
CVE-2024-34095Same product: Adobe Acrobat
CVE-2024-30305Same product: Adobe Acrobat
CVE-2025-43574Same product: Adobe Acrobat
CVE-2023-44371Same product: Adobe Acrobat
CVE-2025-43573Same product: Adobe Acrobat

Affected Assets

adobe
acrobat dc
15.008.20082 — 21.001.20150 · 15.008.20082 — 21.001.20149
adobe
acrobat reader dc
15.008.20082 — 21.001.20150 · 15.008.20082 — 21.001.20149
adobe
acrobat
17.011.30059 — 17.011.30194 · 20.001.30005 — 20.001.30020
adobe
acrobat reader
17.011.30059 — 17.011.30194 · 20.001.30005 — 20.001.30020

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
prevents

Routine patching removes known use-after-free instances after they have been introduced in released software.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect use-after-free bugs before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates memory-safety practices that reduce use-after-free defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-management rules that mitigate use-after-free.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles include memory-safety design choices that limit use-after-free exposure.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe avoidance of use-after-free patterns.

A.8.32 Change management partial match
prevents

Change-management processes help ensure memory-safety fixes are deployed consistently.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416

References