CVE-2023-0040

What it is

Versions of Async HTTP Client prior to 1.13.2 are vulnerable to a form of targeted request manipulation called CRLF injection. This vulnerability was the result of insufficient validation of HTTP header field values before sending them to the network. Users are vulnerable if they pass untrusted data into HTTP header field values without prior sanitisation. Common use-cases here might be to place usernames from a database into HTTP header fields. This vulnerability allows attackers to inject new HTTP header fields, or entirely new requests, into the data stream. This can cause requests to be understood very differently by the remote server than was intended. In general, this is unlikely to result in data disclosure, but it can result in a number of logical errors and other misbehaviours.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-01-18 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 05:24 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-01-18 19:15 UTC

Last modified

2026-06-17 05:24 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-93

Record status

Modified

Affected

• Asynchttpclient Project async-http-client < 1.4.1
• Asynchttpclient Project async-http-client < 1.9.1
• Asynchttpclient Project async-http-client < 1.12.1
• Asynchttpclient Project async-http-client < 1.13.2

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-0040.md and follow it. Check whether this project is affected by CVE-2023-0040. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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