Vulnerability in svelte (CVE-2026-42567)
Summary
Vulnerability in svelte (CVE-2026-42567). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.55.7 or later.
Original description
The description as published by the source.
An internal regex in the Svelte runtime can take exponential time to test in ``. You are only vulnerable to this if you allow tags of unconstrained length. If your application only allows a predetermined list of tags or trims their length before passing them to svelte:element, you are safe.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42567 has been found in svelte.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade svelte to 5.55.7 or later.
If unsure, ask your IT team or search "svelte CVE-2026-42567" on the vendor's site.
CVE-2026-42567 (svelte) — CWE-1333 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 5.55.7 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-1333) exists in svelte.
Check the vendor advisory for the affected versions of svelte.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 5.55.7.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'svelte' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'svelte' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
svelteを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade svelte to 5.55.7ステージング環境で 5.55.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- patch security-advisories@github.com
- web security-advisories@github.com
- web github.com