PT-2026-35895 · Curl+3 · Curl+4

Daniel Stenberg · CVE-2026-6276 · Published 2026-04-29 · Updated 2026-07-21

Positive Technologies (AI Summary)

CVSS v2.0

7.8

High

Base vector

AV:N/AC:L/Au:N/C:N/I:N/A:C

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

DoS

Origin Validation Error

Cleartext Transmission of Sensitive Information

Weakness Enumeration

CWE-346

CWE-319

Related Identifiers

BDU:2026-09774

CVE-2026-6276

ECHO-78B1-43AB-D59F

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

USN-8227-1

Affected Products

Linuxmint

Red Os

Ubuntu

Curl

Libcurl

References · 68

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6276.json · Exploit
• 🔥 https://hackerone.com/reports/3671818 · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-5773 · Security Note
• https://osv.dev/vulnerability/CVE-2026-6276 · Vendor Advisory
• https://curl.se/docs/CVE-2026-6276.html · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:2703-1 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/USN-8227-1 · Vendor Advisory
• https://osv.dev/vulnerability/CURL-CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-11-CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-13-CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/BELL-CVE-2026-6276 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-OS-DEBIAN-12-CVE-2026-6276 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-6253 · Security Note