CVE-2026-27606: Rollup 4 has Arbitrary File Write via Path Traversal

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-25 · updated 2026-09-10
Weakness: CWE-22

Description

Rollup is a module bundler for JavaScript. Versions prior to 2.80.0, 3.30.0, and 4.59.0 of the Rollup module bundler (specifically v4.x and present in current source) is vulnerable to an Arbitrary File Write via Path Traversal. Insecure file name sanitization in the core engine allows an attacker to control output filenames (e.g., via CLI named inputs, manual chunk aliases, or malicious plugins) and use traversal sequences (`../`) to overwrite files anywhere on the host filesystem that the build process has permissions for. This can lead to persistent Remote Code Execution (RCE) by overwriting critical system or user configuration files. Versions 2.80.0, 3.30.0, and 4.59.0 contain a patch for the issue.

Affected products

rollup: before 2.80.0; from 3.0.0 before 3.30.0; from 4.0.0 before 4.59.0 — fixed in 2.80.0, 3.30.0, 4.59.0

How to fix

Upgrade to a fixed version: rollup 2.80.0, 3.30.0, 4.59.0. Check the vendor advisory for mitigations.

References

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