PT-2026-35895 · Curl+2 · Curl+3

Daniel Stenberg · Published 2026-04-29 · Updated 2026-05-29 · CVE-2026-6276

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

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

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

Description When using libcurl, a flaw exists where a custom Host: header set for an initial HTTP request can cause subsequent requests using the same easy handle to use stale information. If the second request is made without a custom Host: header, it may leak cookies intended for the first host.

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

Origin Validation Error

Weakness Enumeration

CWE-319

CWE-346

Related Identifiers

CVE-2026-6276

ECHO-78B1-43AB-D59F

OESA-2026-2477

OPENSUSE-SU-2026:10674-1

RHSA-2026:12916

USN-8227-1

Affected Products

Linuxmint

Ubuntu

Curl

Libcurl

References · 43

• 🔥 https://hackerone.com/reports/3671818 · Exploit
• https://ubuntu.com/security/CVE-2026-6253 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-6276 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-5773 · Security Note
• https://ubuntu.com/security/CVE-2026-6429 · Vendor Advisory
• https://osv.dev/vulnerability/BELL-CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/CURL-CVE-2026-6276 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-6276 · Vendor Advisory
• https://curl.se/docs/CVE-2026-6276.html · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-6253 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-7168 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-6276 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2026-6276 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-5545 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-6429 · Security Note