HOMEVULNERABILITIESCVE-2019-18802
CRITICAL

CVE-2019-18802

NVD-CWE-noinfoPublished: December 13, 2019· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2019-18802 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

envoyproxy1 product(s)
envoy
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/envoyproxy/envoy/commits/master
PATCHhttps://github.com/envoyproxy/envoy/commits/master
ADVISORYhttps://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4
ADVISORYhttps://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4

All References (10)

→
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html
→
https://blog.envoyproxy.ioProduct
→
https://github.com/envoyproxy/envoy/commits/masterPatch
→
https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4Exploit · Third Party Advisory
→
https://groups.google.com/forum/#%21forum/envoy-users
→
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html
→
https://blog.envoyproxy.ioProduct
→
https://github.com/envoyproxy/envoy/commits/masterPatch
→
https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4Exploit · Third Party Advisory
→
https://groups.google.com/forum/#%21forum/envoy-users

Quick Facts

CVE IDCVE-2019-18802
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessNVD-CWE-noinfo
CISA KEVNo
Affected1 vendor(s)
PublishedDec 13, 2019

Related CVEs (NVD-CWE-noinfo)

CVE-2009-4072
10.0
CVE-2009-4294
10.0
CVE-2009-3935
10.0
CVE-2009-3842
10.0
CVE-2009-3847
10.0
CVE-2009-4368
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2019-18802 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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