What’s Vulnerable › Vulnerabilities

CVE-2021-33197

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-08-02 · updated 2026-06-17
• Weakness: CWE-862

Description

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

Affected products

• Go: before 1.15.13; from 1.16.0 before 1.16.5 — fixed in 1.15.13, 1.16.5

How to fix

Upgrade to a fixed version: Go 1.15.13, 1.16.5. Check the vendor advisory for mitigations.

References

• https://groups.google.com/g/golang-announce
• https://groups.google.com/g/golang-announce/c/RgCMkAEQjSI
• https://security.gentoo.org/glsa/202208-02
• https://groups.google.com/g/golang-announce
• https://groups.google.com/g/golang-announce/c/RgCMkAEQjSI
• https://security.gentoo.org/glsa/202208-02

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