Quick answers
- Is CVE-2026-123568 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123568 being exploited in the wild.
- How severe is CVE-2026-123568?
- Medium severity, with a CVSS score of 4.4, published 8 November 2026.
- Which products and versions are affected?
- Sveltejs Devalue before 5.6.3.
- Is there a fix for CVE-2026-123568?
- Yes: fixed in 5.6.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123568 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-123568?
- Check whether you run Sveltejs Devalue at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 5.6.3
Technical details
The uneval function in devalue before 5.6.3 generates code that, when eval'd, creates objects with polluted prototypes if supplied with untrusted input. This is a prototype pollution vulnerability (CWE-1321) with a network attack vector, though it requires high attack complexity and high privileges. An attacker can cause the output data shape to differ from the input, potentially affecting application logic that relies on object structure validation.
Affected products
- Sveltejs devalue before 5.6.3
Timeline
- 2026-02-18: disclosed
- 2026-11-08: advisory