CVE-2023-0040Network attack vector

HTTP request injection via unvalidated header values

Published Jan 18, 2023 · Updated Apr 3, 2025

CRLF injection in Swift Project AsyncHTTPClient affected releases before 1.13.2 allows attackers to alter outbound HTTP requests. RequestValidation validates header names but fails to reject carriage returns, line feeds, and other control bytes in field values before serialization. Exploitation requires untrusted data to reach an outbound header value; attackers can add headers or requests and cause integrity-affecting application logic errors.

CVSS severity7.5
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in Swift Project AsyncHTTPClient affected releases before 1.13.2 allows attackers to alter outbound HTTP requests. RequestValidation validates header names but fails to reject carriage returns, line feeds, and other control bytes in field values before serialization. Exploitation requires untrusted data to reach an outbound header value; attackers can add headers or requests and cause integrity-affecting application logic errors.

The record

CVE
CVE-2023-0040
Published
Jan 18, 2023
Updated
Apr 3, 2025
Vendor
Swift Project
Product
AsyncHTTPClient
Classifications
CWE-74, CWE-93
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <=1.13.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Swift Project · AsyncHTTPClientversion=unspecified <=1.13.1

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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