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Servers and applications

CVE-2019-9900

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.

Severity
High 8.3
Published
25 Apr 2019
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Exploit chance
3.7% in the next 30 daysHigher than 89% of CVEs. EPSS by FIRST, 10 Nov 2026
Sources
NVD

Affected software

SoftwareAffected versions
EnvoyServers and applications · cpe:a:envoyproxy:envoy
  • Every version up to 1.9.0

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2019-9900
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2019-9900