CVE-2020-25017

Severity: high (CVSS 8.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-10-01 · updated 2026-06-17

Description

Envoy through 1.15.0 only considers the first value when multiple header values are present for some HTTP headers. Envoy’s setCopy() header map API does not replace all existing occurences of a non-inline header.

Affected products

envoyproxy envoy: before 1.12.7; from 1.13.0 before 1.13.4; from 1.14.0 before 1.14.4; from 1.15.0 before 1.15.1 — fixed in 1.12.7, 1.13.4, 1.14.4, 1.15.1

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.12.7, 1.13.4, 1.14.4, 1.15.1. Check the vendor advisory for mitigations.

References

https://github.com/envoyproxy/envoy/security/advisories/GHSA-2v25-cjjq-5f4w
https://groups.google.com/forum/#%21forum/envoy-security-announce
https://github.com/envoyproxy/envoy/security/advisories/GHSA-2v25-cjjq-5f4w
https://groups.google.com/forum/#%21forum/envoy-security-announce

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