# CVE-2026-126423: OpenEMR before 8.5.0 Denial of Service via ZIP Upload Decompression

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

OpenEMR before 8.5.0 contains a denial of service vulnerability in four ZIP upload paths that read uncompressed entries into memory without size or ratio checks. Authenticated billing or Carecoordination users can upload highly compressed ZIP archives to exhaust PHP memory and worker pools, making OpenEMR unavailable.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- openemr / openemr: ≥ 0; < 8.5.0 (affected, semver); 8.5.0 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L; source: CNA: VulnCheck

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.37% as of 2026-11-13; percentile 31.76%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-409

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/openemr/openemr/security/advisories/GHSA-pqmf-m4h6-wjh4 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/openemr-before-8.5.0-denial-of-service-via-zip-upload-decompression (CNA: VulnCheck; third-party-advisory)

- https://github.com/openemr/openemr/security/advisories/GHSA-pqmf-m4h6-wjh4 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/openemr-before-8.5.0-denial-of-service-via-zip-upload-decompression (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-126423; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126423; retrieved 2026-11-13; source updated 2026-11-13

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-126423; retrieved 2026-11-13; source updated Not reported

Revision: 0c82fbd38a9c6ff4c851efa17ccf526ce67260d6ded6f7da795f714343474556

Canonical: https://y2.dev/cve/CVE-2026-126423

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.