CVE-2022-43551Public exploitNetwork attack vector

Cleartext transfer via inconsistent IDN normalization

Published Dec 23, 2022 · Updated Feb 13, 2026

HSTS bypass in curl 7.77.0 through 7.86.0 allows remote attackers to cause cleartext HTTP transfers via an IDN hostname. The HSTS cache stores the IDN-encoded hostname but later checks the IDN-decoded form, so an equivalent hostname containing U+3002 misses the stored policy. Exposure requires an IDN-enabled build and a crafted hostname used across successive requests; transmitted data then loses HTTPS protection.

CVSS severity7.5
High
EPSS probability16.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HSTS bypass in curl 7.77.0 through 7.86.0 allows remote attackers to cause cleartext HTTP transfers via an IDN hostname. The HSTS cache stores the IDN-encoded hostname but later checks the IDN-decoded form, so an equivalent hostname containing U+3002 misses the stored policy. Exposure requires an IDN-enabled build and a crafted hostname used across successive requests; transmitted data then loses HTTPS protection.

The record

CVE
CVE-2022-43551
Published
Dec 23, 2022
Updated
Feb 13, 2026
Vendor
curl
Product
curl
Classifications
CWE-319, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 23, 2022CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2026Record 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=Fixed in curl 7.87.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

curl · curlversion=Fixed in curl 7.87.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-319Cleartext Transmission of Sensitive Information
T1040Network Sniffing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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