Adobe InCopy up to 19.5.5/21.0 File heap-based overflow

Summaryinfo

A vulnerability was found in Adobe InCopy up to 19.5.5/21.0. It has been rated as critical. This affects an unknown function of the component File Handler. The manipulation leads to heap-based overflow. This vulnerability is referenced as CVE-2026-21281. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Adobe InCopy up to 19.5.5/21.0. It has been rated as critical. This issue affects an unknown function of the component File Handler. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

InCopy versions 21.0, 19.5.5 and earlier are affected by a Heap-based Buffer Overflow vulnerability 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.

The advisory is shared at helpx.adobe.com. The identification of this vulnerability is CVE-2026-21281 since 12/12/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/14/2026).

The vulnerability scanner Nessus provides a plugin with the ID 283677 (Adobe InCopy < 20.5.1 / 21.0 < 21.1.0 Arbitrary code execution (APSB26-04)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (283677). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Adobe

Name

• InCopy

Version

• 19.5.0
• 19.5.1
• 19.5.2
• 19.5.3
• 19.5.4
• 19.5.5
• 21.0

License

• commercial

Website

• Vendor: https://www.adobe.com/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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