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VulnerabilityPublished Updated

CVE-2026-42570: sveltejs devalue · Unthrottled Resource Allocation

Affects sveltejs devalueSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 5.8.1 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade sveltejs devalue to 5.8.1.

Affected software

ProductAffectedFixed in
sveltejsdevalueAffected
  • >=5.6.3 <5.8.1
Fixed in
  • 5.8.1
npmdevaluepkg:npm/devalueOther threatsAffected
  • >=5.6.3 <5.8.1
Fixed in
  • 5.8.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in sveltejs devalue version 5.8.1. Users should upgrade to version 5.8.1 or later to remediate this vulnerability. The Red Hat advisory confirms the issue and the availability of a patch. No additional mitigation steps are indicated or required beyond applying the official fix.

Description

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. From version 5.6.3 to before version 5.8.1, devalue.parse could, due to quirks in some JavaScript engines, be convinced to allocate much more memory than was needed when deserializing sparse arrays, leading to excessive memory consumption. This issue has been patched in version 5.8.1.

References

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