TI-2026-05503 Aliases CVE-2026-6276 GHSA-2jc6-hc33-hv48

stale custom cookie host causes cookie leak

HIGH 72CWE-346Published 2026-05-13 · Updated 2026-09-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Security bypass, Information disclosure
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 1 fixed, 13 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-346 and CWE-319.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00295 22nd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial curl (curl): 8.14.2, 8.16.1, 8.20.0Red Hat: 1 advisoryRed Hat: 1 fixed, 13 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
curl	curl	7.71.0 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.20.0	8.14.2, 8.16.1, 8.20.0	Patch available	CNA
curl	curl	8.19.0; 8.18.0; 8.17.0; 8.16.0; 8.15.0; 8.14.1; 8.14.0; 8.13.0; 8.12.1; 8.12.0; 8.11.1; 8.11.0; 8.10.1; 8.10.0; 8.9.1; 8.9.0; 8.8.0; 8.7.1; 8.7.0; 8.6.0; 8.5.0; 8.4.0; 8.3.0; 8.2.1; 8.2.0; 8.1.2; 8.1.1; 8.1.0; 8.0.1; 8.0.0; 7.88.1; 7.88.0; 7.87.0; 7.86.0; 7.85.0; 7.84.0; 7.83.1; 7.83.0; 7.82.0; 7.81.0; 7.80.0; 7.79.1; 7.79.0; 7.78.0; 7.77.0; 7.76.1; 7.76.0; 7.75.0; 7.74.0; 7.73.0; 7.72.0; 7.71.1; 7.71.0	—	No fix listed	CNA

curl Vendorcurl Affected 7.71.0 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.20.0 Fixed in 8.14.2, 8.16.1, 8.20.0 Patch available CNA
curl Vendorcurl Affected 8.19.0; 8.18.0; 8.17.0; 8.16.0; 8.15.0; 8.14.1; 8.14.0; 8.13.0; 8.12.1; 8.12.0; 8.11.1; 8.11.0; 8.10.1; 8.10.0; 8.9.1; 8.9.0; 8.8.0; 8.7.1; 8.7.0; 8.6.0; 8.5.0; 8.4.0; 8.3.0; 8.2.1; 8.2.0; 8.1.2; 8.1.1; 8.1.0; 8.0.1; 8.0.0; 7.88.1; 7.88.0; 7.87.0; 7.86.0; 7.85.0; 7.84.0; 7.83.1; 7.83.0; 7.82.0; 7.81.0; 7.80.0; 7.79.1; 7.79.0; 7.78.0; 7.77.0; 7.76.1; 7.76.0; 7.75.0; 7.74.0; 7.73.0; 7.72.0; 7.71.1; 7.71.0 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:haxx:curl::::::::	7.71.0 to before 8.20.0	Vulnerable	Haxx

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* Versions 7.71.0 to before 8.20.0 Vulnerable ·Haxx

Remediation

Fix · CNA curl (curl) Fixed in 8.14.2, 8.16.1, 8.20.0

Red Hat 1 advisory

RHSA-2026:12916 Released 2026-05-02 · Red Hat rating Moderate
Red Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images curl-8.20.0-0.1.hum1@aarch64, curl-8.20.0-0.1.hum1@src, curl-8.20.0-0.1.hum1@x86_64 +6

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-05-13
curl 8.14.2, 8.16.1, 8.20.0
7 records Highest priority Priority HIGH 2 HIGH, 2 MEDIUM, 3 LOW
Other records, highest priority first
- TI-2026-05056 wrong reuse of SMB connectionPriority HIGH 72
- TI-2026-06291 cross-proxy Digest auth state leakPriority MEDIUM 63
- TI-2026-05486 proxy credentials leak over redirect-to proxyPriority MEDIUM 60
Show all 7 records →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

Product	Status	Plan or fix
Confidential Compute Attestation	Affected	No fix yet: Fix deferred
Logging Subsystem for Red Hat OpenShift	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 10	Affected	No fix yet
Red Hat Enterprise Linux 6	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 7	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet
Red Hat Enterprise Linux AI (RHEL AI) 3	Affected	No fix yet: Fix deferred
Red Hat JBoss Core Services	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	—
Red Hat OpenShift Container Platform 4	Affected	No fix yet: Fix deferred
Red Hat OpenShift Dev Spaces	Affected	No fix yet: Fix deferred
Red Hat Trusted Profile Analyzer	Affected	No fix yet: Fix deferred
Red Hat Hardened Images	Fixed	RHSA-2026:12916

Not affected: 4 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 9
Red Hat Hardened Images
Red Hat OpenShift AI (RHOAI)

Timeline

2026-10-02 Threatist record created from CVE-2026-6276
2026-10-03 Alias added: GHSA-2jc6-hc33-hv48
2026-11-07 Affected versions changed · Red Hat

References

TI-2023-19922 Out-of-bounds write in curl CVSS 3.1CRITICAL 9.8
TI-2026-16162 Negotiate ambient user conn reuse CVSS 3.1CRITICAL 9.8
TI-2026-10231 cross-origin Digest auth state leak CVSS 3.1CRITICAL 9.8
TI-2026-09063 HTTP/2 stream-dependency tree UAF CVSS 3.1CRITICAL 9.8
TI-2026-07976 stale proxy password leak CVSS 3.1CRITICAL 9.8
TI-2026-07845 SASL double-free CVSS 3.1CRITICAL 9.8

See all 103 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences