CVE-2026-4873

connection reuse ignores TLS requirement

MEDIUM
5.9
CVSS Score
Published: May 13, 2026 at 08:27 AM UTC
Updated: September 15, 2026 at 07:35 AM UTC
1 product affected across 1 vendorCurl

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Severity
MEDIUM5.9
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

Vendor Advisory
Source: cverecord
https://curl.se/docs/CVE-2026-4873.json
PatchVendor Advisory
Source: cverecord
https://curl.se/docs/CVE-2026-4873.html
ExploitIssue TrackingThird Party Advisory
Source: cverecord
https://hackerone.com/reports/3621851
Mailing ListPatchThird Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/04/29/7

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.9MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-295CWE-319

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