Cyber Resilience

CVE-2024-9681

Haxx Curl 7.74.0 – 8.11.0

Public PoC
Published
06 November 2024
Modified
03 November 2025
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L
EPSS Score 0.020 79th percentile
Risk Priority 54 floored blend · peak EPSS

Summary

CVE-2024-9681 is a medium-severity Incorrect Comparison (CWE-697) vulnerability in Haxx Curl. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Obfuscated Files or Information (T1027); ranked in the top 21% of CVEs by exploit likelihood; 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 SA-11 (Developer Testing and Evaluation) and AC-25 (Reference Monitor) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

When curl is asked to use HSTS, the expiry time for a subdomain might overwrite a parent domain's cache entry, making it end sooner or later than otherwise intended. This affects curl using applications that enable HSTS and use URLs…

more

with the insecure `HTTP://` scheme and perform transfers with hosts like `x.example.com` as well as `example.com` where the first host is a subdomain of the second host. (The HSTS cache either needs to have been populated manually or there needs to have been previous HTTPS accesses done as the cache needs to have entries for the domains involved to trigger this problem.) When `x.example.com` responds with `Strict-Transport-Security:` headers, this bug can make the subdomain's expiry timeout *bleed over* and get set for the parent domain `example.com` in curl's HSTS cache. The result of a triggered bug is that HTTP accesses to `example.com` get converted to HTTPS for a different period of time than what was asked for by the origin server. If `example.com` for example stops supporting HTTPS at its expiry time, curl might then fail to access `http://example.com` until the (wrongly set) timeout expires. This bug can also expire the parent's entry *earlier*, thus making curl inadvertently switch back to insecure HTTP earlier than otherwise intended.

CWE(s)
CWE-697

Related Threats

MITRE ATT&CK Enterprise Techniques

T1027 Obfuscated Files or Information Stealth
Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-10536Same product: Haxx Curl
CVE-2026-9080Same product: Haxx Curl
CVE-2026-3805Same product: Haxx Curl
CVE-2026-8925Same product: Haxx Curl
CVE-2025-15224Same product: Haxx Curl
CVE-2026-1965Same product: Haxx Curl
CVE-2026-3784Same product: Haxx Curl
CVE-2026-5773Same product: Haxx Curl
CVE-2026-11586Same product: Haxx Curl
CVE-2026-6253Same product: Haxx Curl

Affected Assets

haxx
curl
7.74.0 — 8.11.0

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation directly exercises security-relevant comparisons to discover incorrect logic.

AC-25 Reference Monitor partial match

A reference monitor must be small and correct, structurally limiting the chance of flawed comparison logic in authorization decisions.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require correct implementation of comparison logic used for access and authentication decisions.

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 development practices directly require correct logic for security comparisons and thereby prevent this class of flaw.

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
finds

Security testing can detect incorrect comparison flaws before deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle includes code review and testing that can catch incorrect comparison logic.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate correct comparison logic for security decisions.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles can require robust comparison mechanisms for access decisions.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address avoiding incorrect comparison operators and logic.

A.8.5 Secure authentication partial match
degrades

Secure authentication mechanisms rely on correct comparison of credentials or tokens.

References