CVE-2026-23866
Whatsapp 2.25.8.0 – 2.26.7.10
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NSummary
CVE-2026-23866 is a medium-severity Improper Verification of Source of a Communication Channel (CWE-940) vulnerability in Whatsapp Whatsapp. Its CVSS base score is 4.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Malicious Link (T1204.001); ranked at the 38th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Other Platforms; in the LLM/Generative AI Risks risk domain.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-26666
Vulnerability Data
Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for iOS v2.25.8.0 to v2.26.15.72 and WhatsApp for Android v2.25.8.0 to v2.26.7.10 could have allowed a user to trigger processing of media content from an arbitrary URL on…
more
another user’s device, including triggering OS-controlled custom URL scheme handlers. We have not seen evidence of exploitation in the wild.
- CWE(s)
AI Security AnalysisAI
- AI Category
- Other Platforms
- Risk Domain
- LLM/Generative AI Risks
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: ai
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vuln enables arbitrary URL processing + custom scheme handlers via crafted WhatsApp messages, directly facilitating malicious link execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires validation of all input (here, AI rich response messages) to reject malformed or unauthorized content such as arbitrary URLs before any processing occurs.
Enforces policy-based information flow rules that can restrict processing of messages whose source or content (e.g., external URLs or custom schemes) has not been explicitly authorized.
Enables monitoring and analysis of message-handling behavior to identify anomalous outbound URL fetches or custom-scheme invocations triggered by received content.
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.
Authentication of users/services/hardware directly enforces source verification for communication channels.
Verifying identity assertions prevents spoofed channel origins but does not cover all channel-establishment scenarios.
Network protections reduce unauthorized channel usage but do not specifically require origin verification at channel setup.
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.
Secure authentication mechanisms verify the identity and origin of communication channel initiators.
Network security controls enforce source verification and channel authentication for incoming communications.
Security of network services includes validating the origin of service requests and connections.
Network segregation limits exposure but does not directly verify source of individual channels.
Cryptography can support channel authentication but does not inherently verify source without proper implementation.
Application security requirements may specify origin checks but do not mandate them.