A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable no

Technical Impact partial

Affected Vendors & Products

Vendors Products
Curl
  • Curl
Haxx
  • Curl

Configuration 1 [-]

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

No data.

References
Link Providers
http://www.openwall.com/lists/oss-security/2026/04/29/7 cve-icon
https://curl.se/docs/CVE-2026-4873.html cve-icon cve-icon cve-icon
https://curl.se/docs/CVE-2026-4873.json cve-icon cve-icon
https://hackerone.com/reports/3621851 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-4873 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-4873 cve-icon
History

Thu, 14 May 2026 14:00:00 +0000

Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
Weaknesses CWE-295
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl

Wed, 13 May 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Wed, 13 May 2026 15:30:00 +0000

Type Values Removed Values Added
References

Wed, 13 May 2026 09:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. A remote attacker could exploit this by initiating an unencrypted connection (via IMAP, SMTP, or POP3) and then making a subsequent request to the same host that requires Transport Layer Security (TLS). Due to incorrect connection reuse, the subsequent request would bypass the TLS requirement, leading to the transmission of sensitive information in cleartext. This vulnerability, categorized as Cleartext Transmission of Sensitive Information (CWE-319), results in information disclosure. A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.
Title curl: curl: Information disclosure due to incorrect TLS connection reuse connection reuse ignores TLS requirement
References

Fri, 01 May 2026 01:45:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl

Fri, 01 May 2026 00:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. A remote attacker could exploit this by initiating an unencrypted connection (via IMAP, SMTP, or POP3) and then making a subsequent request to the same host that requires Transport Layer Security (TLS). Due to incorrect connection reuse, the subsequent request would bypass the TLS requirement, leading to the transmission of sensitive information in cleartext. This vulnerability, categorized as Cleartext Transmission of Sensitive Information (CWE-319), results in information disclosure.
Title curl: curl: Information disclosure due to incorrect TLS connection reuse
Weaknesses CWE-319
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N'}

threat_severity

Moderate
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published: 2026-05-13T08:27:04.538Z

Updated: 2026-05-13T19:30:04.825Z

Reserved: 2026-03-26T05:38:02.098Z

Link: CVE-2026-4873

cve-icon Vulnrichment

Updated: 2026-05-13T09:05:12.559Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-13T13:01:55.893

Modified: 2026-05-14T13:45:11.407

Link: CVE-2026-4873

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-29T00:00:00Z

Links: CVE-2026-4873 - Bugzilla