TI-2026-08387 Aliases CVE-2026-9545 GHSA-6v72-wfcj-jv53

exposing HTTP/3 early data

HIGH 72CWE-200Published 2026-07-03 · Updated 2026-09-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Information disclosure
Confidentiality · integrity · availability: High · None · None
Fix status: Partial Red Hat: 2 fixed, 13 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-200.

Summary

In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate. When libcurl returns to the hostname the second time with a cached SSL session (`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the `CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might send off the second request's bytes on that new connection *before* enforcing the certificate verification failure. Potentially leaking sensitive information.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00408 35th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial curl (curl): 8.14.2, 8.16.1, 8.20.1Red Hat: 2 advisoriesRed Hat: 2 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	8.11.0 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.20.1	8.14.2, 8.16.1, 8.20.1	Patch available	CNA
curl	curl	8.20.0; 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	—	No fix listed	CNA

curl Vendorcurl Affected 8.11.0 to before 8.14.2; 8.15.0 to before 8.16.1; 8.17.0 to before 8.20.1 Fixed in 8.14.2, 8.16.1, 8.20.1 Patch available CNA
curl Vendorcurl Affected 8.20.0; 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 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:haxx:curl::::::::	8.11.0 to before 8.21.0	Vulnerable	Haxx

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* Versions 8.11.0 to before 8.21.0 Vulnerable ·Haxx

Remediation

Fix · CNA curl (curl) Fixed in 8.14.2, 8.16.1, 8.20.1

Red Hat 2 advisories

RHSA-2026:56869 Released 2026-08-19 · Red Hat rating Important
Red Hat JBoss Core Services Apache HTTP Server 2.4.62 SP5 security update
- Red Hat JBoss Core Services 2.4.62.SP5
RHSA-2026:41240 Released 2026-07-17 · Red Hat rating Moderate
Red Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images curl-8.21.0-0.1.1.hum1@aarch64, curl-8.21.0-0.1.1.hum1@src, curl-8.21.0-0.1.1.hum1@x86_64 +6

Fixed in the same release

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

Release · 2026-07-03
curl 8.14.2, 8.16.1, 8.20.1
13 records Highest priority Priority HIGH 12 HIGH, 1 MEDIUM
Other records, highest priority first
- TI-2026-10231 cross-origin Digest auth state leakPriority HIGH 82
- TI-2026-09063 HTTP/2 stream-dependency tree UAFPriority HIGH 82
- TI-2026-07976 stale proxy password leakPriority HIGH 82
Show all 13 records →

Vendor assessments

Red Hat

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

Product	Status	Plan or fix
Confidential Compute Attestation	Affected	No fix yet
Red Hat Enterprise Linux 10	Affected	No fix yet
Red Hat Enterprise Linux 6	Affected	No fix yet
Red Hat Enterprise Linux 7	Affected	No fix yet
Red Hat Enterprise Linux 8	Affected	No fix yet
Red Hat Enterprise Linux 9	Affected	No fix yet
Red Hat Enterprise Linux AI (RHEL AI) 3	Affected	No fix yet
Red Hat JBoss Core Services	Affected	No fix planned: Will not fix
Red Hat OpenShift AI (RHOAI)	Affected	—
Red Hat OpenShift Container Platform 4	Affected	No fix yet
Red Hat OpenShift Container Platform 5	Affected	No fix yet
Red Hat OpenShift Dev Spaces	Affected	No fix yet
Red Hat Trusted Profile Analyzer	Affected	No fix yet
Red Hat Hardened Images	Fixed	RHSA-2026:41240
Red Hat JBoss Core Services 2.4.62.SP5	Fixed	RHSA-2026:56869

Not affected: 5 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Hardened Images
Red Hat OpenShift AI (RHOAI)

Timeline

2026-10-02 Threatist record created from CVE-2026-9545
2026-10-03 Alias added: GHSA-6v72-wfcj-jv53
2026-10-09 Fix available: RHSA-2026:56869 · Red Hat
2026-10-16 Fix available: Red Hat JBoss Core Services 2.4.62.SP5 · Red Hat
2026-10-30 Affected versions changed · Red Hat
2026-11-06 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