CVE-2026-21277
Published: 13 January 2026
Summary
CVE-2026-21277 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Adobe Indesign. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 6.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-21277 is a heap-based buffer overflow vulnerability (CWE-122, CWE-787) affecting Adobe InDesign Desktop versions 21.0, 19.5.5, and earlier. Published on 2026-01-13, the issue carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H) and could result in arbitrary code execution in the context of the current user.
Exploitation requires user interaction, as a victim must open a malicious file to trigger the vulnerability. Local attackers with no privileges needed can deliver such a file, exploiting the low-complexity flaw to achieve high-impact confidentiality, integrity, and availability effects within the user's scope, without privilege escalation.
Adobe's security bulletin APSB26-02, available at https://helpx.adobe.com/security/products/indesign/apsb26-02.html, addresses the vulnerability with details on patches and mitigations.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2072
Vulnerability details
InDesign Desktop 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…
more
must open a malicious file.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Buffer overflow in desktop app enables arbitrary code execution via malicious file opened by user (T1204.002); directly matches client-side exploitation technique (T1203).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates CVE-2026-21277 by requiring identification, reporting, and correction of the heap-based buffer overflow flaw through vendor patches for InDesign.
Implements memory safeguards such as ASLR and DEP to prevent arbitrary code execution from the heap buffer overflow during malicious file processing.
Ensures timely receipt and implementation of Adobe security bulletins like APSB26-02 addressing the InDesign vulnerability.