Cyber Resilience

CVE-2026-11352

DoS in Haxx Curl 8.18.0 – 8.21.0

Public PoCDoS
Published
03 July 2026
Modified
07 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0058 44th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-11352 is a high-severity Infinite Loop (CWE-835) vulnerability in Haxx Curl. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SC-5 (Denial-of-service Protection) and SC-7 (Boundary Protection) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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…

more

packet budget, a connected QUIC peer can continuously stream empty datagrams to indefinitely stall the client.

CWE(s)
CWE-835

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Why these techniques?

Vulnerability description directly describes remote DoS via application exploitation of the QUIC receive logic.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2025-5399Same product: Haxx Curl
CVE-2026-3805Same product: Haxx Curl
CVE-2026-11586Same product: Haxx Curl
CVE-2026-6429Same product: Haxx Curl
CVE-2026-8926Same product: Haxx Curl
CVE-2026-9079Same product: Haxx Curl
CVE-2026-9545Same product: Haxx Curl
CVE-2025-15224Same product: Haxx Curl
CVE-2025-14017Same product: Haxx Curl
CVE-2025-13034Same product: Haxx Curl

Affected Assets

haxx
curl
8.18.0 — 8.21.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SC-7 Boundary Protection
  • SC-5 Denial-of-service Protection
Detect
Catch it (NIST detect / respond)
  • SI-4 System Monitoring
Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SC-7 Boundary Protection good match
prevent

Boundary protection at the network perimeter can filter or rate-limit the flood of empty UDP datagrams before they reach the vulnerable QUIC receive path in curl.

SC-5 Denial-of-service Protection good match
prevent

Denial-of-service protection mechanisms can detect and throttle the continuous stream of zero-length UDP packets that cause the client to stall indefinitely.

SI-4 System Monitoring partial match
detect

System monitoring can observe anomalous QUIC/UDP traffic patterns indicative of the empty-datagram DoS and trigger alerts or automated responses.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (reviews, testing, static analysis) directly prevent introduction of infinite-loop defects.

ID.RA-01 partial match
prevents

Static analysis and vuln scanning during asset assessment can detect unreachable loop exits.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
detects

Security testing can uncover infinite-loop conditions before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates practices that can detect and prevent infinite-loop defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify loop-termination rules, indirectly reducing the weakness.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address loop termination and prevent infinite loops.

A.8.27 Secure system architecture and engineering principles none match
none

Secure architecture principles encourage designs that avoid unreachable exit conditions.

A.8.32 Change management none match
none

Change management can require review of loop logic when code is modified.

References