CVE-2026-6276

HIGH

curl 8.7.0-8.19.0 - Sensitive Cookie Leak via Stale Host Header

Title source: llm

Description

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.

References (4)

Core 4

Core References

json

https://curl.se/docs/CVE-2026-6276.json

www

https://curl.se/docs/CVE-2026-6276.html

issue

https://hackerone.com/reports/3671818

Mailing List

http://www.openwall.com/lists/oss-security/2026/04/29/13

Scores

CVSS v3 7.5

EPSS 0.0001

EPSS Percentile 2.1%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment

Exploitation poc

Automatable yes

Technical Impact partial

Details

CWE

CWE-319

Status published

Products (50)

curl/curl 7.71.0

curl/curl 7.71.1

curl/curl 7.72.0

curl/curl 7.73.0

curl/curl 7.74.0

curl/curl 7.75.0

curl/curl 7.76.0

curl/curl 7.76.1

curl/curl 7.77.0

curl/curl 7.78.0

... and 40 more

Published May 13, 2026

Tracked Since May 13, 2026