CVE-2022-43552Network attack vector

Client crash via freed proxy-tunnel state

Published Feb 9, 2023 · Updated Oct 27, 2024

Use-after-free in curl 7.16.0 through 7.86.0 allows remote attackers controlling an HTTP proxy to crash the client during tunnel denial. When an SMB or TELNET tunnel is denied, its done handler frees protocol-specific request state that transfer shutdown later reuses. Reachability requires a tunneled SMB or TELNET transfer through a hostile HTTP proxy; the bounded consequence is client process termination.

CVSS severity5.9
Medium
EPSS probability2.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in curl 7.16.0 through 7.86.0 allows remote attackers controlling an HTTP proxy to crash the client during tunnel denial. When an SMB or TELNET tunnel is denied, its done handler frees protocol-specific request state that transfer shutdown later reuses. Reachability requires a tunneled SMB or TELNET transfer through a hostile HTTP proxy; the bounded consequence is client process termination.

The record

CVE
CVE-2022-43552
Published
Feb 9, 2023
Updated
Oct 27, 2024
Vendor
curl
Product
curl
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 27, 2024Record 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

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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