7.5

CVE-2026-42570: Svelte devalue: DoS via sparse array deserialization

Modified
AliasesGHSA-77vg-94rm-hx3p
Published 09-06-2026Last modified 24-08-2026

Vulnerability summary

CVE-2026-42570 is a high (CVSS 7.5) vulnerability in svelte devalue. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 33.9% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.40%
0%100%
Low · -0.32 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1
RHSA-2026:57590

Timeline

  1. 09-06-2026
    PublishedVulnerability first disclosed.
  2. 24-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.40%

Chance of exploitation in the next 30 days

Percentile

34%

Versus all other CVEs

30-day change

Decrease -0.32 pp

From 0.72% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Npm1 product
  • devalue≥ 5.6.3, < 5.8.1
Svelte1 product
Sveltejs1 product

3 vendors · 3 products

References

10 links