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Vulnerabilities

Vulnerability · CVE-2026-30226

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job.

Published Mar 11, 2026 · catalog updated Jun 17, 2026 · Svelte devalue is a

Check if you run it

No confirmed exploitation is on record for CVE-2026-30226. EPSS is 0.55%. Act only if a listed version of Svelte devalue is a is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Svelte devalue is a).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.55%
Remediation
Version ranges on file
Affected products
cpe svelte/devalue · stated devalue

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe svelte/devalueversion unspecified
  • stated devalue<= 6.3

How to fix CVE-2026-30226

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-30226. EPSS is 0.55%. Act only if a listed version of Svelte devalue is a is installed.

Which versions are affected?

Compare what you have installed with <= 6.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). EPSS 0.55%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 11, 2026 · NIST NVD

    Detected

    Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

  2. Jun 17, 2026 · NIST NVD

    Updated

    Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

Sources

  • CVE.orgVulnerability recordCVE-2026-30226

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-30226

    30-day exploitation probability 0.6%

    first.org
  • NIST NVDVulnerability recordCVE-2026-30226

    Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exp

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.