CVE-2025-57820 Svelte devalue vulnerable to prototype pollution
Attackers can pollute object prototypes via crafted strings in devalue.parse, potentially leading to code execution or privilege escalation in Svelte applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-57820?
CVE-2025-57820 is a high-severity vulnerability in sveltejs devalue, published on 26 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Svelte devalue is a utility library. Prior to version 5.3.2, a string passed to devalue.parse could represent an object with a __proto__ property and devalue.parse does not check that an index is numeric. This could result in assigning prototypes to objects and properties, leading to prototype pollution. This issue has been fixed in version 5.3.2
Weakness: CWE-1321
Which versions are affected by CVE-2025-57820?
2 open source packages ship an affected version, including devalue.
| Package | Affected | Fixed in |
|---|---|---|
devalue npm | All versions | 5.3.2 |
devalue npm | All versions | 5.3.2 |
How do I fix CVE-2025-57820?
Upgrade devalue to 5.3.2 or later.
Is CVE-2025-57820 being exploited?
There is no known exploitation of CVE-2025-57820 in the wild and no public exploit code.
Sources
Also known as CLSA-2026-1774398079, GHSA-vj54-72f3-p5jv, ROOT-APP-NPM-CVE-2025-57820.