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CVE-2026-123562

8.7
High
EPSS n/aPatch available

Devalue bug allows attacker-controlled async values to crash Node.js via unhandled rejection.

exploited
No known exploitation not in CISA KEV as of our last sync
fix
Fixed in 5.9.3
likelihood
No EPSS score yet
Published 8 Nov 2026Analysed here 8 Nov 2026CVSS scored by the publisher (CNA)

do firstUpgrade to a fixed release: 5.9.3.

common questions

Is CVE-2026-123562 being exploited?

Not confirmed. CVE-2026-123562 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked.

How severe is CVE-2026-123562?

CVE-2026-123562 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-123562?

Yes. A fix has been recorded for CVE-2026-123562. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-123562 affect?

CVE-2026-123562 affects sveltejs/devalue < 5.9.3, Node.js applications that bundle devalue (<5.9.3). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-123562?

Upgrade devalue to >=5.9.3 and restart affected Node.js services.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
sveltejs/devalue < 5.9.3Node.js applications that bundle devalue (<5.9.3)
impact

Remote/attacker-influenced denial-of-service: crafted async values can cause unhandled promise rejection that terminates Node.js processes.

action required

Patch when possible

affected versions
sveltejs devalue
  • affected>= 5.8.0 and < 5.9.3
vendor says fixed in5.9.3

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

timeline

  1. 8 Nov 2026Published
  2. 8 Nov 2026CVE record last updated · same day later
  3. 8 Nov 2026Analysed by vulneraibility.com · same day later
how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
NVDCVE.orgCVE DetailsSource
2 references in the CVE record: 2 advisories
  • Advisorygithub.com /sveltejs/devalue/security/advisories/GHSA-x5rw-q4pp-hg5g
  • Advisoryvulncheck.com /advisories/devalue-5.8.0-before-5.9.3-denial-of-service-via-stringifyasync-unha

sources

  • CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
  • NVD: CVSS and CPE data
  • FIRST EPSS: exploit probability and percentile
  • Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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