CVE-2019-18802
CVE-2019-18802 is a critical-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v2: 7.5
- EPSS exploit prediction: 2% (82nd percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Envoyproxy Envoy
- Published:
- Last modified:
Description
An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat "header-value " as a different string from "header-value" so for example with the Host header "example.com " one could bypass "example.com" matchers.
Frequently asked questions
- What is CVE-2019-18802?
- An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat "header-value " as a different string from "header-value" so for example with the Host header "example.com " one could bypass "example.com" matchers.
- How severe is CVE-2019-18802?
- CVE-2019-18802 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2019-18802 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2019-18802?
- CVE-2019-18802 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2019-18802?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2019-18802 published?
- CVE-2019-18802 was published on 2019-12-13 and last updated on 2026-06-17.
References
- http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html
- https://blog.envoyproxy.io
- https://github.com/envoyproxy/envoy/commits/master
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4
- https://groups.google.com/forum/#%21forum/envoy-users
Affected products (1)
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
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