TI-2026-09799 Aliases CVE-2026-11352 GHSA-qxwx-hr5v-h5q4

QUIC zero-length UDP datagrams busy-loop

HIGH 72CWE-835Published 2026-07-03 · Updated 2026-09-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-835.

Summary

An issue in curl’s QUIC UDP receive function allows a malicious HTTP/3 server to trigger a remote denial of service against a curl or libcurl client. Because the helper function discards zero-length UDP datagrams before counting them toward the per-call packet budget, a connected QUIC peer can continuously stream empty datagrams to indefinitely stall the client.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.0101 63rd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed curl (curl): 8.20.1Red Hat: 2 advisories

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	8.18.0 to before 8.20.1	8.20.1	Patch available	CNA
curl	curl	8.20.0; 8.19.0; 8.18.0	—	No fix listed	CNA

curl Vendorcurl Affected 8.18.0 to before 8.20.1 Fixed in 8.20.1 Patch available CNA
curl Vendorcurl Affected 8.20.0; 8.19.0; 8.18.0 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:haxx:curl::::::::	8.18.0 to before 8.21.0	Vulnerable	Haxx

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* Versions 8.18.0 to before 8.21.0 Vulnerable ·Haxx

Remediation

Fix · CNA curl (curl) Fixed in 8.20.1

Red Hat 2 advisories

RHSA-2026:34975 Released 2026-07-02 · Red Hat rating Important
Red Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images cargo-1.96.1-1.hum1@aarch64, cargo-1.96.1-1.hum1@x86_64, clippy-1.96.1-1.hum1@aarch64 +36
RHSA-2026:29017 Released 2026-06-24 · Red Hat rating Important
Red Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images curl-8.21.0-0.1.hum1@aarch64, curl-8.21.0-0.1.hum1@src, curl-8.21.0-0.1.hum1@x86_64 +6

Fixed in the same release

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

Release · 2026-07-03
curl 8.20.1
3 records Highest priority Priority HIGH 3 HIGH
Other records, highest priority first
- TI-2026-09987 Native CA trust persistPriority HIGH 74
- TI-2026-08388 sending old refererPriority HIGH 72
Show all 3 records →

Vendor assessments

Red Hat

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

Product	Status	Plan or fix
Red Hat Hardened Images	Fixed	RHSA-2026:29017, RHSA-2026:34975

Not affected: 10 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat JBoss Core Services
Red Hat OpenShift Container Platform 4
Red Hat OpenShift Container Platform 5
Red Hat OpenShift Dev Spaces
Red Hat Trusted Profile Analyzer

Timeline

2026-10-02 Threatist record created from CVE-2026-11352
2026-10-03 Alias added: GHSA-qxwx-hr5v-h5q4
2026-10-30 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