CVE-2026-5545
Haxx Curl 7.10.6 – 8.20.0
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:NSummary
CVE-2026-5545 is a medium-severity Insufficient Session Expiration (CWE-613) vulnerability in Haxx Curl. Its CVSS base score is 6.5 (Medium).
Operationally, ranked at the 34th 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 AC-12 (Session Termination) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-29923
Vulnerability Data
libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host. libcurl features a pool of recent connections so that subsequent requests can reuse…
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an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. An application that first uses Negotiate authentication to a server with `user1:password1` and then does another operation to the same server asking for any authentication method but for `user2:password2` (while the previous connection is still alive) - the second request gets confused and wrongly reuses the same connection and sends the new request over that connection thinking it uses a mix of user1's and user2's credentials when it is in fact still using the connection authenticated for user1...
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Insufficient information to map techniques.CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Enforces per-request credential validation so that a pooled Negotiate-authenticated connection cannot be silently reused for a different user identity to the same host.
Forces automatic termination of authenticated sessions, directly mitigating the CWE-613 session-reuse flaw that allows the stale Negotiate connection to remain valid for the wrong credentials.
Requires re-authentication before a subsequent request with different credentials, preventing libcurl from reusing the prior Negotiate-authenticated connection.
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.
Credential lifecycle management directly includes enforcing session expiration to prevent reuse.
Authorization policy enforcement and review covers terminating stale sessions to limit access scope.
Authentication mechanisms can incorporate session timeout checks but do not inherently address expiration policy.
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.
Automatic termination of inactive sessions and limits on connection duration shrink the window during which a hijacked or unattended authenticated session can be exploited.