ZDI made the advisory ZDI-26-400 public on July 13, 2026, for a 0-day vulnerability in AnyDesk, identified as CVE-2026-15681 with a CVSS score of 4.7. The vendor has not released a fix despite a coordinated disclosure process lasting 16 months, which culminated in the issue being classified as "out of scope" in December 2025.
The forced publication by a leading bug-bounty program raises immediate questions about security supply-chain management for remote-access software, a category especially sensitive for the enterprise perimeter.
- ZDI published advisory ZDI-26-400 on July 13, 2026, for a 0-day vulnerability in AnyDesk, with CVE-2026-15681 assigned and CVSS 4.7.
- The flaw allows a local attacker with low-privileged code to cause denial-of-service by manipulating screen-recording files via an NTFS junction.
- Coordinated disclosure began March 25, 2025; after 16 months the vendor declared the issue "out of scope" on December 11, 2025.
- No patch exists at the time of publication: the advisory was released as a 0-day with the vendor neither confirming nor releasing a fix.
The Mechanism: How a Junction on Recording Files Blocks the Service
The vulnerability lies in how AnyDesk handles screen-recording files. According to the advisory's technical documentation, creating a junction — an NTFS reparse point that redirects a path to another location in the filesystem — allows an attacker to divert the service's write operations to arbitrary destinations.
The result is the unauthorized overwriting or creation of files, leading to denial-of-service of the functionality. This class of bug, known as link following, is documented in Windows applications that fail to properly validate paths before file operations.
"The specific flaw exists within the handling of screen recording files. By creating a junction, an attacker can abuse the service to create arbitrary files" — ZDI Advisory ZDI-26-400
The requirement for local access with low privileges reduces the attack surface compared to remote vectors, but does not eliminate it in enterprise environments where shared accounts, public terminals, or partial compromises are real scenarios.
The Timeline of a Failed Disclosure: 16 Months Without Response
The timeline documented by ZDI shows a coordinated disclosure process that broke on the vendor's response. The initial report was sent on March 25, 2025. On December 11, 2025, AnyDesk's support team communicated that the issue was "out of their scope."
Nine months after that classification, on July 13, 2026, ZDI proceeded with 0-day publication of the advisory. The total time window — from report to public disclosure — exceeds 16 months, a span that far exceeds standard industry expectations for handling vulnerabilities reported through coordinated channels.
"the vendor's support team communicated that the issue was out of their scope" — ZDI Advisory ZDI-26-400, timeline note
The CVSS 4.7 assigned by ZDI places the vulnerability in the low-to-medium range, reflecting the local-access requirement and the impact limited to denial-of-service. The score does not, however, account for the temporal factor of the missing fix nor the public availability of technical details.
The Risk for Enterprise Environments Using Remote Desktop
AnyDesk is widely deployed in corporate contexts, from IT help desks to remote technical support infrastructures. The combination of remote access with session recording — the exact vulnerable surface — is a common configuration for audit and compliance.
An attacker with local presence on an endpoint running AnyDesk can interfere with screen-recording files, inducing a targeted DoS. In multi-stage attack scenarios, this capability can disrupt evidence collection or halt the support software at critical moments.
The dossier does not specify whether the creation of "arbitrary files" can be extended beyond the stated denial-of-service. The advisory explicitly indicates only DoS as impact, and ZDI has not documented privilege escalation or other effects.
Why This Matters
The publication of ZDI-26-400 documents a pattern of vendor "security fatigue": the reclassification of a valid report as "out of scope" after months of operational inertia. This behavior exposes users who cannot independently mitigate a known but unpatched vulnerability.
The source does not specify affected AnyDesk versions, nor alternative mitigations. The brief does not document official AnyDesk responses to the 0-day publication nor the presence of exploits in the wild. The nature of the bug — local, low-privileged, limited to DoS — reduces immediate criticality but not the systemic relevance for a category of software that manages remote sessions with potential access to sensitive systems.
The tension between responsible disclosure and vendor accountability remains the dominant theme: when a remote-access infrastructure provider declines to handle a flaw reported through institutional channels, the researcher is forced into a binary choice between public disclosure and indefinite silence.
Frequently Asked Questions
Is it necessary to uninstall AnyDesk?
The dossier does not document specific mitigations or vendor recommendations. The mitigation decision depends on the assessment of local DoS risk in your operational context.
Which AnyDesk versions are vulnerable?
Advisory ZDI-26-400 does not list specific affected versions. The brief notes as a limitation that affected versions are not documented in the primary source.
Can the attack be executed remotely?
No. The advisory specifies that the attacker must obtain "the ability to execute low-privileged code on the target system." The vector is local.
Information is based on the cited advisory and current as of publication.
Sources
- http://www.zerodayinitiative.com/advisories/ZDI-26-400/
- http://www.zerodayinitiative.com/advisories/published/
Information is based on the cited source and current as of publication.