CVE-2026-123568sveltejs devalue prototype pollution
CVE-2026-123568 is a prototype pollution in sveltejs devalue, rated low (2.1 on CVSS 4.0).
Why this priority: Low severity, with no exploitation signal.
Published · Updated · NVD status: Received
What it is
Input can change JavaScript object prototypes, altering behaviour across the application.
How it is reached
An attacker can exploit it over the network, with an administrator account, and nobody has to click anything. Success also depends on conditions the attacker does not fully control.
What an attacker gains
The direct impact is limited: partial access to data or a partial outage. In practice, this kind of flaw lets an attacker turn crafted data into code execution inside the receiving service. The damage can spread past the vulnerable component into others.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade sveltejs devalue to 5.6.3 or later.
- Until it is patched, review who holds accounts that can reach it.
Description from NVD
Sveltejs 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.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- APIs, queues and caches that accept serialized objects. The flaw sits between a message producer and the service that deserializes it.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- Between a message producer and the service that deserializes it. An attacker who crosses it can turn crafted data into code execution inside the receiving service.
Questions to answer about your own systems
- Where does sveltejs devalue run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.