docs: document symlink permission behavior#2958
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bartlomieju merged 4 commits intodenoland:mainfrom Mar 9, 2026
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Adds a new section under File System Access explaining how Deno handles permissions for symbolic links: - Permissions are checked on symlink location, not target - Escalation prevention for sensitive paths (/proc, /dev, /sys) - Safe device files that are always accessible - Symlink creation requires full read+write permissions - Pre-existing symlinks are not subject to creation restrictions
lucacasonato
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Mar 6, 2026
runtime/fundamentals/security.md
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| > what your code can create and access, not what already exists on the | ||
| > filesystem. |
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This is a confusing phrasing - "The permission model only governs what your code can create and access," - except that "access" is goverened by the symlink location not the target location, which then , which then feels weird if you say "not what already exists on the FS" (because it's exactly about what is already on the FS).
Address review feedback - the previous phrasing was confusing about what 'access' means vs 'create'.
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Adds documentation for how Deno handles permissions for symbolic links, addressing https://github.com/denoland/deno/security/advisories/GHSA-jxwh-q9gp-f7j9.
Changes
Adds a new "Symbolic links" subsection under "File system access" that explains:
/proc,/dev,/sys)/proc/**/environ(requires--allow-env)/dev/null,/dev/zero, etc.) are always accessible--allow-readand--allow-writeThis clarifies the security model around symlinks so users understand the expected behavior.