Home/CVE/Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done u
CVE

CVE-2026-6276

Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done u

Using libcurl, when a custom Host: header is first set for an HTTP request and a second request is subsequently done using the same easy handle but without the custom Host: header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

HIGH · CVSS 7.5 EPSS 0.00013
Act now
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules7 YARA rules0
⬡

Weakness Classification

CWE-319Cleartext Transmission of Sensitive Information
▤

Affected Products & Versions

1
haxx curl>= 7.71.0 and < 8.20.0
⚠

Public Exploits & PoCs

1
pochackerone.com · 3671818hackerone.com
◈

Sigma Hunt Rules

7
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSuspicious Download and Execute Pattern via Curl/Wget
producthighSuspicious File Download From File Sharing Domain Via Curl.EXE
producthighSuspicious File Download From IP Via Curl.EXE
producthighCurl Download And Execute Combination
producthighSuspicious Curl.EXE Download
productmediumSuspicious Curl File Upload - Linux
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · 2499f714-1537-4658-8207-48ae4bb9eae9
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD13 May 2026 · 01:01 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

7
suse-csafSUSE-SU-2026:1940-1
msrcCVE-2026-6276
suse-csafSUSE-SU-2026:1717-1
usnUSN-8227-1
suse-csafopenSUSE-SU-2026:10674-1
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://curl.se/docs/CVE-2026-6276.htmlPatchVendor Advisory
https://curl.se/docs/CVE-2026-6276.jsonProduct
http://www.openwall.com/lists/oss-security/2026/04/29/13Mailing ListThird Party Advisory
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