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CVE-2026-6276

Haxx Curl vulnerability

7.5 HIGHPublic exploitEPSS 0.35%
  1. Published13 May 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Haxx Curl≥ 7.71.0 < 8.20.0

Remediation

Fixed in
Haxx Curl≥ 8.20.0

References

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Frequently asked

Is CVE-2026-6276 being actively exploited?

CVE-2026-6276 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.35%.

How severe is CVE-2026-6276?

CVE-2026-6276 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.35% probability of exploitation.

Which products are affected by CVE-2026-6276?

Affected products include Haxx Curl.

How do I fix CVE-2026-6276?

Upgrade affected software to a fixed version, for example Haxx Curl 8.20.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-6276 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.