7.5

CVE-2026-42567: Svelte: ReDoS in `<svelte:element>` Tag Validation

Analyzed
AliasesGHSA-9rmh-mm8f-r9h6
Published 09-06-2026Last modified 09-06-2026

Vulnerability summary

CVE-2026-42567 is a high (CVSS 7.5) vulnerability in svelte. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 39.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.9, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.45%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

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

Description

Svelte is a performance oriented web framework. From version 5.51.5 to before version 5.55.7, an internal regex in the Svelte runtime can take exponential time to test in <svelte:element this={tag}></svelte:element>. This issue has been patched in version 5.55.7.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

39%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.44% 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, administrative account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Npm1 product
  • svelte≥ 5.51.5, < 5.55.7
Svelte1 product
Sveltejs1 product

3 vendors · 3 products

References

4 links