CVE-2026-21853 AFFiNE: One-click Remote Code Execution through Custom URL Handling
Attackers can achieve remote code execution on victim machines by tricking them into visiting a malicious site or clicking a crafted link that triggers the AFFiNE custom URL handler.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-21853?
CVE-2026-21853 is a high-severity code injection vulnerability in toeverything AFFiNE, published on 2 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
AFFiNE is an open-source, all-in-one workspace and an operating system. Prior to version 0.25.4, there is a one-click remote code execution vulnerability. This vulnerability can be exploited by embedding a specially crafted affine: URL on a website. An attacker can trigger the vulnerability in two common scenarios: 1/ A victim visits a malicious website controlled by the attacker and the website redirect to the URL automatically, or 2/ A victim clicks on a crafted link embedded on a legitimate website (e.g., in user-generated content). In both cases, the browser invokes AFFiNE custom URL handler, which launches the AFFiNE app and processes the crafted URL. This results in arbitrary code execution on the victim’s machine, without further interaction. This issue has been patched in version 0.25.4.
Weakness: CWE-94
Which versions are affected by CVE-2026-21853?
It affects 1 product.
Products include Affine Affine.
How do I fix CVE-2026-21853?
No fix has been published for CVE-2026-21853 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-21853 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21853 exists.
Other vulnerabilities in toeverything AFFiNE
Sources
Also known as GHSA-67vm-2mcj-8965.