🛡️ CVE-2026-33228 on Debian — node-flatted

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.

Distribution advisory

This page covers CVE-2026-33228 as tracked by Debian, for the package node-flatted. The fix is available in version 3.4.2~ds-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

DEBIAN-CVE-2026-33228 is classified as CWE-1321: Prototype Pollution. Attacker input can modify an object prototype, changing behaviour for objects across the application.

Affected software

DEBIAN-CVE-2026-33228 is recorded against 1 package.

  • node-flatted (fixed in 3.4.2~ds-1)

Timeline and source

Published on 20 March 2026 and last revised on 5 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2026-33228 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-03-20
Updated 2026-08-12
Modified 2026-08-05
Fix URL N/A

Affected Packages

Software From version Fixed in
node-flatted — 3.4.2~ds-1

Similar Threats

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