PT-2026-35891 · Curl+3 · Curl+3

Arkadi Vainbrand + 1 · CVE-2026-4873 · Published 2026-04-29 · Updated 2026-07-21

Positive Technologies (AI Summary)

CVSS v3.1

5.9

Medium

Base vector

AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Name of the Vulnerable Software and Affected Versions curl (affected versions not specified)

Description A flaw exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is performed in clear-text via IMAP, SMTP, or POP3, a subsequent request to the same host bypasses the TLS requirement and transmits data unencrypted.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

Cleartext Transmission of Sensitive Information

Improper Certificate Validation

Weakness Enumeration

CWE-319

CWE-295

Related Identifiers

BDU:2026-09770

CVE-2026-4873

ECHO-597F-0D7C-A9E6

OESA-2026-2477

OPENSUSE-SU-2026:10674-1

OPENSUSE-SU-2026:20973-1

RHSA-2026:12916

SUSE-SU-2026:1717-1

SUSE-SU-2026:1940-1

SUSE-SU-2026:21452-1

SUSE-SU-2026:22146-1

SUSE-SU-2026:22156-1

SUSE-SU-2026:2703-1

SUSE-SU-2026:2925-1

USN-8227-1

Affected Products

Linuxmint

Red Os

Ubuntu

Curl

References · 89

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4873.json · Exploit
• 🔥 https://hackerone.com/reports/3621851 · Exploit
• https://curl.se/docs/CVE-2026-4873.html · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:2703-1 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-11-CVE-2026-4873 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-4873 · Vendor Advisory
• https://osv.dev/vulnerability/CURL-CVE-2026-4873 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-8227-1 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-4873 · Vendor Advisory
• https://osv.dev/vulnerability/ALPINE-CVE-2026-4873 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-4873 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2026:20973-1 · Vendor Advisory
• http://openwall.com/lists/oss-security/2026/04/29/7 · Patch
• https://osv.dev/vulnerability/SUSE-SU-2026:22146-1 · Vendor Advisory