Secuno
ENNL
Book demo

CVE-2026-11856

Haxx Curl authentication bypass

9.8 CRITICALPublic exploitEPSS 0.69%
  1. Published3 Jul 2026

Description

Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then changing the origin to a different one (`hostB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Authorization:` header field meant for `hostA`, to `hostB`.

CVSS 3.1 breakdown

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

Affected products

Haxx Curl≥ 7.10.6 < 8.21.0

Remediation

Fixed in
Haxx Curl≥ 8.21.0

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-736368.1
Authentication bypass by capture-replay in mod_auth_digest in Apache Software…
CVE-2026-779678.1
The Botslab G980H dash camera firmware accepts a reusable authentication value without…
CVE-2026-541488.1
http4k is a functional toolkit for Kotlin HTTP applications. Prior to 4.51.0.0,…
CVE-2026-882789.8
GeoVision GV-LPC2211 V1.13 fails to enforce WS-Security UsernameToken freshness or…
CVE-2026-696768.8
Authentication bypass by capture-replay in Windows Kerberos allows an authorized…
CVE-2026-862199.8
Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed…

Frequently asked

Is CVE-2026-11856 being actively exploited?

CVE-2026-11856 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.69%.

How severe is CVE-2026-11856?

CVE-2026-11856 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.69% probability of exploitation.

Which products are affected by CVE-2026-11856?

Affected products include Haxx Curl.

How do I fix CVE-2026-11856?

Upgrade affected software to a fixed version, for example Haxx Curl 8.21.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-11856 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.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

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