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Fencer Vulns
high 7.5

CVE-2023-0040 json

Async HTTP Client has CRLF Injection vulnerability in HTTP request headers

published 2023-01-18 3 y ago modified 2026-07-08 4 mo ago also EUVD-2023-1887 , GHSA-v3r5-pjpm-mwgq

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 47%
public exploits
0
none known

Summary

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.

Patch / fix

  • swift github.com/swift-server/async-http-client 1.4.1, 1.9.1, 1.12.1, 1.13.2
  • asynchttpclient_project async-http-client 1.4.1, 1.9.1, 1.12.1, 1.13.2

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.56% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
swift github.com/swift-server/async-http-client
>=1.13.0, <1.13.2
>=1.10.0, <1.12.1
>=1.5.0, <1.9.1
<1.4.1
1.13.2
1.12.1
1.9.1
1.4.1

Affected products

  • Swift Project Async HTTP Client

Classification

Weakness
  • CWE-93 Improper Neutralization of CRLF Sequences
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.