CVE-2026-11856: cross-origin Digest auth state leak

Critical severity · published Jul 3, 2026

CVE-2026-11856

cross-origin Digest auth state leak

9.8

CVSS

0.7%

EPSS

On KEV

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 vector

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.7% · higher than 53% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

curl · curl

7.10.6 before 8.14.2; 8.15.0 before 8.16.1; 8.17.0 before 8.20.1; 334d78cd18a7310144383929bdcef34ffbf6159b before 5c6b4880357ab3e72967c1c45cae0f96ffabc535; 8.20.0; 8.19.0; +34 more · source: vendor, NVD

In the news

VulnerabilityHigh

Hitachi Energy RTU500 Product

View CSAF Summary Hitachi Energy is aware of vulnerabilities that affect RTU500 product versions listed in this document. These vulnerabilities if exploited can have impact on confidentiality, integrity and availability of the product. Please refer to the Recommended Immediate Actions for information about the mitigation/remediation. The following versions of Hitachi Energy RTU500 Product are affected: RTU500 series CMU Firmware vers:RTU500_series_CMU_Firmware/>=13.5.1|<=13.5.4, vers:RTU500_series_CMU_Firmware/>=13.6.1|<=13.6.3, vers:RTU500_series_CMU_Firmware/>=13.7.1|<=13.7.8, vers:RTU500_series_CMU_Firmware/>=13.8.1|<=13.8.2, vers:RTU500_series_CMU_Firmware/>=12.7.1|<=12.7.7 (CVE-2026-17539, CVE-2026-28388, CVE-2026-6732, CVE-2026-6653, CVE-2026-6276, CVE-2026-9079, CVE-2026-11856, CVE-2026-8927, CVE-2026-8932, CVE-2026-17539, CVE-2026-28388, CVE-2026-6732, CVE-2026-6653, CVE-2026-6276, CVE-2026-9079, CVE-2026-11856, CVE-2026-8927, CVE-2026-8932, CVE-2026-17539, CVE-2026-28388, CVE-2026-6732, CVE-2026-6653, CVE-2026-6276, CVE-2026-9079, CVE-2026-11856, CVE-2026-8927, CVE-2026-8932, CVE-2026-17539, CVE-2026-28388, CVE-2026-6732, CVE-2026-6653, CVE-2026-6276, CVE-2026-9079, CVE-2026-11856, CVE-2026-8927, CVE-2026-8932, CVE-2026-17539, CVE-2026-28388, CVE-2026-6653) CVSS Vendor Equipment v3 8.8 Hitachi Energy RTU500 series CMU Firmware 7 Vulnerabilities NULL Pointer Dereference, ...

CVE-2026-17539 CVE-2026-28388 CVE-2026-6732

Oct 20, 2026·US-CERT ICS Advisories

Affected product

curl

All curl CVEs

References

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-11856

CVE.org

https://www.cve.org/CVERecord?id=CVE-2026-11856

Patch

https://curl.se/docs/CVE-2026-11856.html

Vendor Advisory

https://curl.se/docs/CVE-2026-11856.json

Exploit

https://hackerone.com/reports/3793260