Vulnerability

CVE-2026-6276

Low· 7.5CVSS7.5EPSS0%

.rules3/5

curl/libcurl: stale custom cookie host causes cookie leak

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.

Threat signal

75/100

High

Severity

low

CVSS

7.5

EPSS

Active

CVSS

v3.1via NVDOpen in FIRST calculator →

7.5/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactNoneNo confidentiality impact.
Integrity ImpactNoneNo integrity impact.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

0.01%

probability of exploitation in next 30 days

higher than 2% of all CVEs

3-day trend↑ 0pp

Low exploitation likelihood — defer if no other signals fire.

Vendor VEX

No VEX statements published for CVE-2026-6276. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCTrack

Total impact on non-trivial mission systems

exploitation: none
automatable: no
impact: total
mission: support

Lifecycle

2026-04-29Published
2026-04-29Last modified2 sources
2026-05-14Vendor advisory · microsoftCVE-2026-6276 — stale custom cookie host causes cookie leak

Entity graph

2 nodes · 1 edges · click to pivot

CVEActorVendor advisoryIOCNews

Vendor advisories

microsoftCVE-2026-6276stale custom cookie host causes cookie leak

References

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.