CVE-2026-81176 Svelte devalue: DoS via malformed input
Attackers can cause denial of service in applications using Svelte devalue by sending specially crafted payloads that trigger quadratic processing time.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-81176?
CVE-2026-81176 is a medium-severity denial of service vulnerability in sveltejs devalue, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. Prior to 5.9.2, devalue.parse does not reject out-of-bounds indices that are greater than or equal to values.length in src/parse.js. A specially crafted untrusted payload can make the parser alternate between array representations, producing quadratic work as the payload grows and causing denial of service in applications that parse untrusted devalue data. This issue is fixed in version 5.9.2.
Weakness: CWE-770
Which versions are affected by CVE-2026-81176?
2 open source packages ship an affected version, including devalue.
| Package | Affected | Fixed in |
|---|---|---|
devalue npm | All versions | 5.9.2 |
devalue npm | All versions | 5.9.2 |
How do I fix CVE-2026-81176?
Upgrade devalue to 5.9.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-81176 being exploited?
There is no known exploitation of CVE-2026-81176 in the wild and no public exploit code.
Sources
Also known as CLSA-2026-1789752547, CLSA-2026-1792231082, CLSA-2026-1792231273, GHSA-9rgm-9g3h-6x36.