StableLib: Prototype poisoning via `__proto__` map keys in CBOR decoding

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-106448
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 20:17:26 UTC
Updated2026-10-06 20:17:26 UTC
DescriptionStableLib is a stable library of useful TypeScript and JavaScript code. Prior to 2.0.4, the @stablelib/cbor CBOR map decoding path creates ordinary JavaScript objects and assigns attacker-controlled keys with bracket assignment. A map key named __proto__ invokes the inherited prototype setter instead of creating an ordinary own property, allowing the decoded object's prototype to contain attacker-controlled authorization or feature-flag values. Downstream code that trusts normal property lookup or merges the decoded object can therefore make security-sensitive decisions using inherited attacker data. This issue is fixed in version 2.0.4.

Risk And Classification

Primary CVSS: v4.0 8.9 HIGH from [email protected]

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-1321 | CWE-1321 CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary8.9HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/C...
4.0CNADECLARED8.9HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
High
Availability
None
Sub Conf.
None
Sub Integrity
High
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA StableLib Stablelib affected < 2.0.4 Not specified

References

ReferenceSourceLinkTags
github.com/StableLib/stablelib/releases/tag/@stablelib/[email protected] [email protected] github.com
github.com/StableLib/stablelib/commit/0f153a63b7552a0e8721f640984113e419... [email protected] github.com
github.com/StableLib/stablelib/security/advisories/GHSA-w48f-fwg7-ww6p [email protected] github.com
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