CVE-2026-6276 — stale custom cookie host causes cookie leak

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
curl / curl	affected 7.71.0 before 8.14.2; affected 8.15.0 before 8.16.1; affected 8.17.0 before 8.20.0
curl / curl	affected e15e51384a423be31318b3c9c7d612a1aae661fd before 3a19987a87f393d9394fe5acc7643f6c263c92db
curl / curl	affected 8.19.0; affected 8.18.0; affected 8.17.0; affected 8.16.0; affected 8.15.0; affected 8.14.1; affected 8.14.0; affected 8.13.0; affected 8.12.1; affected 8.12.0; affected 8.11.1; affected 8.11.0; affected 8.10.1; affected 8.10.0; affected 8.9.1; affected 8.9.0; affected 8.8.0; affected 8.7.1; affected 8.7.0; affected 8.6.0; affected 8.5.0; affected 8.4.0; affected 8.3.0; affected 8.2.1; affected 8.2.0; affected 8.1.2; affected 8.1.1; affected 8.1.0; affected 8.0.1; affected 8.0.0; affected 7.88.1; affected 7.88.0; affected 7.87.0; affected 7.86.0; affected 7.85.0; affected 7.84.0; affected 7.83.1; affected 7.83.0; affected 7.82.0; affected 7.81.0; affected 7.80.0; affected 7.79.1; affected 7.79.0; affected 7.78.0; affected 7.77.0; affected 7.76.1; affected 7.76.0; affected 7.75.0; affected 7.74.0; affected 7.73.0; affected 7.72.0; affected 7.71.1; affected 7.71.0

CWE

CWE-346

References

ADP enrichment

CVE

No English description supplied.

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

CISA-ADP

No English description supplied.

https://hackerone.com/reports/3671818