CVE-2021-39839
Acrobat Reader DC versions 2021.005.20060 (and earlier), 2020.004.30006 (and earlier) and 2017.011.30199 (and earlier) are affected by a use-after-free vulnerability in the processing of the AcroForm getItem action that could result in 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.
Vulnerability Summary
CVSS v3 Score
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS v2 Score
AV:N/AC:M/Au:N/C:P/I:P/A:P
EPSS Score (Exploitation Probability)
This vulnerability has a 45.46% probability of being exploited in the next 30 days, ranking higher than 98% of all scored CVEs.
CWE Classification
Related Vulnerabilities
Same Weakness Type(CWE-416)
Use after free in Dawn in Google Chrome prior to 146.0.7680.178 allowed a remote attacker who had compromised the renderer process to execute arbitrary code via a crafted HTML page. (Chromium security severity: High)
Use after free in CSS in Google Chrome prior to 145.0.7632.75 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page. (Chromium security severity: High)
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, offscreen bitmap deletion leaves `gdi->drawing` pointing to freed memory, causing UAF when related update packets arrive. A malicious server can trigger a client‑side use after free, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, `xf_Pointer_New` frees `cursorPixels` on failure, then `pointer_free` calls `xf_Pointer_Free` and frees it again, triggering ASan UAF. A malicious server can trigger a client‑side use after free, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.
Use After Free vulnerability was discovered in fs/vfs/fs_rename code of the Apache NuttX RTOS, that due recursive implementation and single buffer use by two different pointer variables allowed arbitrary user provided size buffer reallocation and write to the previously freed heap chunk, that in specific cases could cause unintended virtual filesystem rename/move operation results. This issue affects Apache NuttX RTOS: from 7.20 before 12.11.0. Users of virtual filesystem based services with write access especially when exposed over the network (i.e. FTP) are affected and recommended to upgrade to version 12.11.0 that fixes the issue.
Similar SeverityHIGH
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
An Improper Input Validation in Ivanti EPMM before versions 12.6.1.1, 12.7.0.1, and 12.8.0.1 allows a remotely authenticated user with administrative access to achieve remote code execution.
OpenClaw before 2026.4.22 contains a server-side request forgery vulnerability in the Zalo plugin's sendPhoto function that fails to validate outbound photo URLs through the SSRF guard. Attackers can bypass SSRF protection by providing malicious photo URLs to the Zalo Bot API, enabling unauthorized access to internal resources.
OpenClaw before 2026.4.22 contains an exec allowlist analysis vulnerability allowing shell expansion hiding in unquoted heredoc bodies. Attackers can bypass allowlist validation by embedding shell expansion tokens in heredoc bodies to execute unapproved commands at runtime.
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