Bug 2453157 (CVE-2026-21716)

Summary: CVE-2026-21716 nodejs: Node.js: Permission bypass allows unauthorized modification of file permissions and ownership via incomplete security fix.
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: caswilli, kaycoth
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Node.js. An incomplete security fix allows code operating under restricted file system write permissions to bypass these limitations. This vulnerability enables the modification of file permissions and ownership on already-open files, even when explicit write access is denied. Such a bypass could lead to unauthorized changes to system files.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2453592, 2453595, 2453594    
Bug Blocks:    

Description OSIDB Bzimport 2026-03-30 20:02:15 UTC 
An incomplete fix for CVE-2024-36137 leaves `FileHandle.chmod()` and `FileHandle.chown()` in the promises API without the required permission checks, while their callback-based equivalents (`fs.fchmod()`, `fs.fchown()`) were correctly patched.

As a result, code running under `--permission` with restricted `--allow-fs-write` can still use promise-based `FileHandle` methods to modify file permissions and ownership on already-open file descriptors, bypassing the intended write restrictions.

This vulnerability affects **20.x, 22.x, 24.x, and 25.x** processes using the Permission Model where `--allow-fs-write` is intentionally restricted.