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CVE-2026-4873

connection reuse ignores TLS requirement

Published: May 13, 2026Updated: May 14, 2026 Sources: CVE List NVDCWE-295
NVD MITRE
5.9CVSSMEDIUM
EPSS Score
0.3%
Top 82.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-295CWE-319

Affected Products

curlhaxxOSS Libraries
curlcurl
Library
OSS Libraries / generic-library
haxxoss-projectSEOSS Librariesaka haxx.se
curloss-projectUSOSS Librariesaka libcurl, wcurl

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Collection
Credential Access
View detailed technique mapping

References

https://curl.se/docs/CVE-2026-4873.html
curl.se
https://curl.se/docs/CVE-2026-4873.json
curl.se
https://hackerone.com/reports/3621851
hackerone.com
and 1 more references View all →

Timeline

Published
May 13, 2026
Last Updated
May 14, 2026

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