CVE-2026-42567
Description
A flaw was found in Svelte, a web framework. An internal regular expression (regex) in the Svelte runtime, specifically when processing <svelte:element this={tag}></svelte:element>, can be exploited by a remote attacker. By providing specially crafted input, an attacker can cause the regex to take an exponential amount of time to process, leading to a Regular Expression Denial of Service (ReDoS) condition. This can make the affected application unresponsive or unavailable to legitimate users.
Statement
A flaw was found in Svelte. An internal regex in the Svelte runtime can take exponential time when processing specially crafted input in <svelte:element this={tag}> elements, leading to a Regular Expression Denial of Service (ReDoS). Red Hat products that ship svelte (Podman Desktop, Konflux) use it as a UI framework and do not expose user-controlled input to the vulnerable regex path in production.
Mitigation
Upgrade to Svelte 5.55.7 or later.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU)
Attackers can create crafted inputs that intentionally cause the regular expression to use excessive backtracking in a way that causes the CPU consumption to spike.
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