Sveltejs devalue before 5.6.3 Prototype Pollution via uneval Output

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-123568
StatePUBLISHED
AssignerVulnCheck
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-08 02:16:49 UTC
Updated2026-11-12 13:17:14 UTC
DescriptionSveltejs devalue before 5.6.3 contains a prototype pollution vulnerability that allows attackers to alter object prototypes by supplying untrusted data to uneval. When the generated code is later evaluated, it creates objects with polluted prototypes, producing output data whose shape differs from the original input.

Risk And Classification

Primary CVSS: v4.0 2.1 LOW from [email protected]

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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

EPSS: 0.002020000 probability, percentile 0.101570000 (date 2026-11-09)

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

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.1LOWCVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/C...
4.0CNACVSS2.1LOWCVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
3.1[email protected]Secondary4.4MEDIUMCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
3.1CNACVSS4.4MEDIUMCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sveltejs Devalue affected 5.6.3 semver Not specified
CNA Sveltejs Devalue unaffected 5.6.3 semver Not specified

References

ReferenceSourceLinkTags
github.com/sveltejs/devalue/security/advisories/GHSA-8qm3-746x-r74r [email protected] github.com
www.vulncheck.com/advisories/sveltejs-devalue-before-5.6.3-prototype-pollution-... [email protected] www.vulncheck.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: elliott-with-the-longest-name-on-github (en)

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