What is CVE-2023-0040?

CVE-2023-0040 is a high-severity security vulnerability in github.com/swift-server/async-http-client (swift), affecting versions >= 1.13.0, < 1.13.2. It is fixed in 1.13.2, 1.12.1, 1.9.1, 1.4.1.

How severe is CVE-2023-0040?

CVE-2023-0040 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of github.com/swift-server/async-http-client are affected by CVE-2023-0040?

github.com/swift-server/async-http-client (swift) versions >= 1.13.0, < 1.13.2 is affected.

Is there a fix for CVE-2023-0040?

Yes. CVE-2023-0040 is fixed in 1.13.2, 1.12.1, 1.9.1, 1.4.1. Upgrade to this version or later.

Is CVE-2023-0040 exploitable, and should I be worried?

Whether CVE-2023-0040 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2023-0040 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2023-0040

Q: How severe is CVE-2023-0040?

CVE-2023-0040 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of github.com/swift-server/async-http-client are affected by CVE-2023-0040?

github.com/swift-server/async-http-client (swift) versions >= 1.13.0, < 1.13.2 is affected.

Q: Is there a fix for CVE-2023-0040?

Yes. CVE-2023-0040 is fixed in 1.13.2, 1.12.1, 1.9.1, 1.4.1. Upgrade to this version or later.

Q: Is CVE-2023-0040 exploitable, and should I be worried?

Whether CVE-2023-0040 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2023-0040 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2023-0040?

Upgrade: github.com/swift-server/async-http-client to 1.13.2 or later, github.com/swift-server/async-http-client to 1.12.1 or later, github.com/swift-server/async-http-client to 1.9.1 or later, github.com/swift-server/async-http-client to 1.4.1 or later.

Summary

Async HTTP Client has CRLF Injection vulnerability in HTTP request headers

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.

Impact

CVE-2023-0040 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.13.2, 1.12.1, 1.9.1, 1.4.1); upgrading removes the vulnerable code path.

Affected versions

github.com/swift-server/async-http-client (>= 1.13.0, < 1.13.2) github.com/swift-server/async-http-client (>= 1.10.0, < 1.12.1) github.com/swift-server/async-http-client (>= 1.5.0, < 1.9.1) github.com/swift-server/async-http-client (< 1.4.1)

Security releases

github.com/swift-server/async-http-client → 1.13.2 (swift) github.com/swift-server/async-http-client → 1.12.1 (swift) github.com/swift-server/async-http-client → 1.9.1 (swift) github.com/swift-server/async-http-client → 1.4.1 (swift)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

github.com/swift-server/async-http-client to 1.13.2 or later; github.com/swift-server/async-http-client to 1.12.1 or later; github.com/swift-server/async-http-client to 1.9.1 or later; github.com/swift-server/async-http-client to 1.4.1 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2023-0040? CVE-2023-0040 is a high-severity security vulnerability in github.com/swift-server/async-http-client (swift), affecting versions >= 1.13.0, < 1.13.2. It is fixed in 1.13.2, 1.12.1, 1.9.1, 1.4.1.
How severe is CVE-2023-0040? CVE-2023-0040 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of github.com/swift-server/async-http-client are affected by CVE-2023-0040? github.com/swift-server/async-http-client (swift) versions >= 1.13.0, < 1.13.2 is affected.
Is there a fix for CVE-2023-0040? Yes. CVE-2023-0040 is fixed in 1.13.2, 1.12.1, 1.9.1, 1.4.1. Upgrade to this version or later.
Is CVE-2023-0040 exploitable, and should I be worried? Whether CVE-2023-0040 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2023-0040 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2023-0040?
- Upgrade github.com/swift-server/async-http-client to 1.13.2 or later
- Upgrade github.com/swift-server/async-http-client to 1.12.1 or later
- Upgrade github.com/swift-server/async-http-client to 1.9.1 or later
- Upgrade github.com/swift-server/async-http-client to 1.4.1 or later