Vulnerability Report

CVE-2026-4873

Title: TLS bypass via unencrypted connection reuse

Information Disclosure

Proof Of Concept

No public PoC currently indexed for CVE-2026-4873.

CWE Category NVD-CWE-noinfo
Published Date May 13, 2026
Modified Date May 14, 2026
Exploit Status Not Found
Score 5.9 CVSS v
Exploit Probability (EPSS)
0.01%

Vulnerability Summary

CVE-2026-4873: 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.

Impacted Vendors

D
daniel_stenberg 1
H
haxx 1

Reference Links

https://curl.se/docs/CVE-2026-4873.html https://curl.se/docs/CVE-2026-4873.json https://hackerone.com/reports/3621851 http://www.openwall.com/lists/oss-security/2026/04/29/7
CVSS v3.1
Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0
Severity MEDIUM
5.9
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-4873 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected Stack

No specific products linked.