When parsing HTTP/1.x header values, Envoy 1.9.0 and before does not reject embedded zero…
Priority MEDIUM 42CWE-74Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
When parsing HTTP/1.x header values, Envoy 1.9.0 and before does not reject embedded zero characters (NUL, ASCII 0x0). This allows remote attackers crafting header values containing embedded NUL characters to potentially bypass header matching rules, gaining access to unauthorized resources.
Why it matters now
EPSS 0.03732 89th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed Red Hat: 1 advisory
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* | up to 1.9.0 | Vulnerable | envoyproxy |
| cpe:2.3:a:redhat:openshift_service_mesh:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Red Hat |
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions up to 1.9.0 Vulnerable ·envoyproxy
- cpe:2.3:a:redhat:openshift_service_mesh:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Red Hat
Remediation
Red Hat 1 advisory
- RHSA-2019:0741 Released 2019-04-10 · Red Hat rating ImportantIstio-Proxy Security Update
- Red Hat OpenShift Service Mesh 0 Tech Preview servicemesh-proxy-0.9.1-1.el7
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift Service Mesh 0 Tech Preview | Fixed | RHSA-2019:0741 |
Timeline
- 2026-10-02 Threatist record created from CVE-2019-9900
- 2026-10-03 Alias added: GHSA-h9r7-c397-3wqr
References
Sources
- CVE-2019-9900 · CVE Program
- CVE-2019-9900 · NVD
- FIRST EPSS
- GHSA-h9r7-c397-3wqr · GitHub Advisory Database · CC BY 4.0
- CVE-2019-9900 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences