What’s Vulnerable › Vulnerabilities

CVE-2020-36632: hughsk flat index.js unflatten prototype pollution

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-12-25 · updated 2026-06-17
• Weakness: CWE-1321

Description

A vulnerability, which was classified as critical, was found in hughsk flat up to 5.0.0. This affects the function unflatten of the file index.js. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). It is possible to initiate the attack remotely. Upgrading to version 5.0.1 is able to address this issue. The name of the patch is 20ef0ef55dfa028caddaedbcb33efbdb04d18e13. It is recommended to upgrade the affected component. The identifier VDB-216777 was assigned to this vulnerability.

Affected products

• hughsk flat: before 5.0.1 — fixed in 5.0.1

How to fix

Upgrade to a fixed version: hughsk flat 5.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/hughsk/flat/commit/20ef0ef55dfa028caddaedbcb33efbdb04d18e13
• https://github.com/hughsk/flat/issues/105
• https://github.com/hughsk/flat/pull/106
• https://github.com/hughsk/flat/releases/tag/5.0.1
• https://vuldb.com/?ctiid.216777
• https://vuldb.com/?id.216777
• https://github.com/hughsk/flat/commit/20ef0ef55dfa028caddaedbcb33efbdb04d18e13
• https://github.com/hughsk/flat/issues/105
• https://github.com/hughsk/flat/pull/106
• https://github.com/hughsk/flat/releases/tag/5.0.1
• https://vuldb.com/?ctiid.216777
• https://vuldb.com/?id.216777

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