6.3
Medium
CVE-2026-123567 Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten
Description
Sveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized input that, when downstream code merges results via Object.assign, alters the target object's prototype.
CVSS 4.0 detail
Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NExploitable remotely over the network, without an account and without any user action; the impact on data or service is limited.
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- None
- Interaction
- None
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
- Confidentiality of other systems
- None
- Integrity of other systems
- None
- Availability of other systems
- None
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| devalue 5.6 | earliest → < 5.6.4 | 5.6.4 |
Other CVEs of devalue
The 16 CVEs of devalue →
CVE-2026-123569
Devalue before 5.6.3 Denial of Service via Sparse Array Serialization
8.7
High
CVE-2026-123568
Sveltejs devalue before 5.6.3 Prototype Pollution via uneval Output
2.1
Low
CVE-2026-123566
Devalue before 5.9.3 CPU Amplification Denial of Service via uneval
8.7
High
CVE-2026-123565
Devalue before 5.9.3 Quadratic Expansion Denial of Service via uneval
8.7
High