CVE-2026-72887
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-72887 is a critical-severity Algorithm Downgrade (CWE-757) vulnerability. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Downgrade Attack (T1689); ranked at the 44th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and SC-8 (Transmission Confidentiality and Integrity) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-59987
Vulnerability Data
Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token. Passing a callback to the constructor selects OAuth 1.0a. get_request_token then revokes that choice when the request token response omits…
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oauth_callback_confirmed, with no exception, no warning and no option to require 1.0a. The access token request is built from the OAuth 1.0 message class, which has no verifier parameter, so oauth_verifier is dropped from the request even when get_access_token was passed one. oauth_verifier is the binding that OAuth 1.0a added between the authorization step and the token exchange. An application that asked for 1.0a and gets 1.0 is open to OAuth 1.0 session fixation, where an attacker obtains a request token, has the victim authorize it, and then completes the exchange themselves, linking the victim's provider account to a session the attacker controls. No attacker action sets up the downgrade: a provider that does not confirm the callback is enough.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 7 hardening rules · 5 OS baselines
V12.1.1V12.2.1V12.3.3V17.2.2
Mitigating Controls (NIST 800-53 r5) AI
Specifying and implementing required cryptography types directly precludes negotiation or acceptance of weaker algorithms.
Requiring protection of transmitted confidentiality and integrity forces selection of sufficiently strong negotiated algorithms rather than weaker ones.
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.AA-04 addresses protection/verification of identity assertions in SSO/federation contexts while CWE-757 concerns protocol-level crypto algorithm negotiation, so the control neither prevents nor meaningfully mitigates the weakness.
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.
Security testing can detect and block algorithm downgrade vulnerabilities before deployment.
Ensures network services use secure cryptographic parameters, reducing downgrade risk.
Mandates use of strong, approved cryptographic algorithms, directly preventing downgrade to weaker ones.
Secure SDLC practices include selecting strong crypto algorithms during design and implementation.
Application security requirements can specify minimum cryptographic strength to avoid downgrades.
Secure architecture principles include enforcing strong algorithm selection in protocol design.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Windows 10 (1 rule)
- V-220938 The LanMan authentication level must be set to send NTLMv2 response only, and to refuse LM and NTLM. prevents CWE-757
Windows 11 (1 rule)
- V-253462 prevents CWE-757
Windows Server 2016 (1 rule)
- V-225054 The LAN Manager authentication level must be set to send NTLMv2 response only and to refuse LM and NTLM. prevents CWE-757
Windows Server 2019 (1 rule)
- V-205919 Windows Server 2019 LAN Manager authentication level must be configured to send NTLMv2 response only and to refuse LM and NTLM. prevents CWE-757
Windows Server 2022 (1 rule)
- V-254475 prevents CWE-757