VulnerabilityPublished 10 Feb 2026Updated 27 Aug 2026

CVE-2026-21358: Adobe InDesign Desktop · Heap-based Buffer Overflow

Affects Adobe InDesign DesktopSource CVE Database V5

Not known to be exploited · CVSS 5.5 Medium.

Data as of 26 Oct 2026, 09:16 UTC

CVSS 3.1 base score

5.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
AdobeInDesign Desktop	Affected <=21.1 <=20.5.1	Fixed in–

AI-suggested

To mitigate CVE-2026-21358, European organizations should implement the following specific measures: 1) Monitor Adobe's security advisories closely and apply patches or updates as soon as they become available to address this vulnerability. 2) Restrict the opening of InDesign files from untrusted or unknown sources, employing email filtering and endpoint controls to reduce the risk of malicious file delivery. 3) Educate users about the risks of opening unsolicited or suspicious files, emphasizing cautious handling of attachments and downloads. 4) Employ application whitelisting and sandboxing techniques to limit the impact of potential crashes and isolate InDesign processes. 5) Use endpoint detection and response (EDR) tools to monitor for unusual application crashes or behaviors that may indicate exploitation attempts. 6) Consider network segmentation for systems running InDesign to contain potential disruptions. 7) Maintain regular backups of critical project files to minimize data loss from unexpected application failures. These targeted actions go beyond generic advice by focusing on controlling file sources, user behavior, and containment strategies specific to this vulnerability.

Description

InDesign Desktop versions 21.1, 20.5.1 and earlier are affected by a Heap-based Buffer Overflow vulnerability that could result in application denial-of-service. An attacker could exploit this vulnerability to crash the application, causing disruption to services. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Impact

For European organizations, the primary impact of CVE-2026-21358 is operational disruption due to application crashes causing denial-of-service. This can affect productivity in sectors heavily reliant on Adobe InDesign, such as media, publishing, advertising, and graphic design. Although the vulnerability does not compromise data confidentiality or integrity, repeated crashes or targeted attacks could lead to significant downtime and workflow interruptions. Organizations that rely on automated or batch processing of InDesign files may experience cascading failures. Additionally, if exploited in a targeted manner, it could be used as a nuisance or distraction vector in broader attack campaigns. The requirement for user interaction limits remote exploitation but does not eliminate risk, especially in environments where users frequently open files from external or untrusted sources. The absence of known exploits reduces immediate risk but does not preclude future weaponization. Overall, the impact is medium, primarily affecting availability and operational continuity.

CWE-122Heap-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #16
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().
Pre-design: Use a language or compiler that performs automatic bounds checking.
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

helpx.adobe.com/security/products/indesign/apsb26-17.html (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Feb 2026, 18:47 UTC

WeaknessesCWE-122

Technical details

References

Community reviews

Related threats