CVE-2019-16276 – CVE-2019-16276 is an HTTP request smuggling vul... (How to Fix)

Q: What is the severity of CVE-2019-16276?

CVE-2019-16276 has a CVSS score of 7.5 (HIGH). CVE-2019-16276 is an HTTP request smuggling vulnerability in Go's net/http package that allows attackers to bypass security controls and potentially poison web caches or hijack user sessions. It affects applications built with Go versions before 1.12.10 and 1.13.x before 1.13.1 that handle HTTP traffic. This vulnerability enables attackers to smuggle malicious requests through front-end proxies to back-end servers.

📋 TL;DR

CVE-2019-16276 is an HTTP request smuggling vulnerability in Go's net/http package that allows attackers to bypass security controls and potentially poison web caches or hijack user sessions. It affects applications built with Go versions before 1.12.10 and 1.13.x before 1.13.1 that handle HTTP traffic. This vulnerability enables attackers to smuggle malicious requests through front-end proxies to back-end servers.

💻 Affected Systems

Products:

Go programming language
Applications built with Go

Versions: Go versions before 1.12.10 and 1.13.x before 1.13.1

Operating Systems: All operating systems running affected Go applications

Default Config Vulnerable: ⚠️ Yes

Notes: Any Go application using the standard net/http package to handle HTTP/1.1 requests is vulnerable. Applications behind HTTP proxies are particularly at risk.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Attackers could poison web caches, hijack user sessions, bypass authentication, or perform cross-site scripting attacks against other users.

🟠

Likely Case

Cache poisoning leading to credential theft or malware distribution through compromised cached content.

🟢

If Mitigated

Limited impact with proper input validation and request sanitization at both proxy and application layers.

🌐 Internet-Facing: HIGH - HTTP servers exposed to the internet are directly vulnerable to request smuggling attacks.

🏢 Internal Only: MEDIUM - Internal applications could be exploited by authenticated attackers or through other compromised systems.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires understanding of HTTP request smuggling techniques and the ability to send crafted HTTP requests to vulnerable servers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Go 1.12.10 or Go 1.13.1

Vendor Advisory: https://golang.org/doc/devel/release#go1.12.10

Restart Required: Yes

Instructions:

1. Update Go installation to version 1.12.10 or 1.13.1 using your package manager or from golang.org. 2. Recompile all Go applications with the updated version. 3. Restart all Go-based services and applications.

🔧 Temporary Workarounds

Use HTTP/2 exclusively

all

Configure servers to only accept HTTP/2 connections, which is not vulnerable to this specific request smuggling attack.

Configure your HTTP server to disable HTTP/1.1 and only accept HTTP/2 connections

Deploy WAF with request validation

all

Implement a web application firewall that validates and sanitizes HTTP requests before they reach the Go application.

🧯 If You Can't Patch

Deploy reverse proxies with strict HTTP request validation and normalization
Implement additional request sanitization middleware in your Go applications

🔍 How to Verify

Check if Vulnerable:

Check Go version with 'go version' command. If output shows version earlier than 1.12.10 or 1.13.x earlier than 1.13.1, the system is vulnerable.

Check Version:

go version

Verify Fix Applied:

Run 'go version' and confirm output shows 1.12.10 or later, or 1.13.1 or later. Test HTTP request handling with known smuggling test vectors.

📡 Detection & Monitoring

Log Indicators:

Unusual HTTP request patterns
Multiple requests with same connection
Malformed HTTP headers in logs
Unexpected 400/413 responses

Network Indicators:

HTTP requests with unusual Content-Length or Transfer-Encoding headers
Requests that appear to contain multiple HTTP messages

SIEM Query:

http.method=* AND (http.content_length:* OR http.transfer_encoding:*) AND (http.status_code=400 OR http.status_code=413)

📊 Metadata

CVE ID: CVE-2019-16276

CVSS v3 Score: 7.5 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CWE: CWE-444

Published: September 30, 2019

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00043.html Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00044.html Mailing List,Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0101 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0329 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0652 Third Party Advisory
https://github.com/golang/go/issues/34540 Patch,Third Party Advisory
https://groups.google.com/forum/#%21msg/golang-announce/cszieYyuL9Q/g4Z7pKaqAgAJ
https://lists.debian.org/debian-lts-announce/2021/03/msg00014.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00015.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LULL72EUUKIY4NWDZVJVN2LIB4MXHS5P/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/O7GMJ3VXF5RXK2C7CL66KJ6XOOTOL5BJ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Q5MD2F7ATWSTB45ZJIPJHBAAHVRGRAKG/
https://security.netapp.com/advisory/ntap-20191122-0004/ Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00043.html Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00044.html Mailing List,Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0101 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0329 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0652 Third Party Advisory
https://github.com/golang/go/issues/34540 Patch,Third Party Advisory
https://groups.google.com/forum/#%21msg/golang-announce/cszieYyuL9Q/g4Z7pKaqAgAJ
https://lists.debian.org/debian-lts-announce/2021/03/msg00014.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00015.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LULL72EUUKIY4NWDZVJVN2LIB4MXHS5P/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/O7GMJ3VXF5RXK2C7CL66KJ6XOOTOL5BJ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Q5MD2F7ATWSTB45ZJIPJHBAAHVRGRAKG/
https://security.netapp.com/advisory/ntap-20191122-0004/ Third Party Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2019-16276, you might also want to check these:

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Cloud Insights Telegraf Agent by Netapp

Debian Linux by Debian

Developer Tools by Redhat

Enterprise Linux by Redhat

Enterprise Linux Eus by Redhat

Fedora by Fedoraproject

Fedora by Fedoraproject

Fedora by Fedoraproject

Go by Golang

Go by Golang

Leap by Opensuse

Leap by Opensuse

Openshift Container Platform by Redhat

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Use HTTP/2 exclusively

Deploy WAF with request validation

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities