Deep Link Hijacking in Microsoft Authenticator
CVE-2026-26123 is a local information disclosure vulnerability in Microsoft Authenticator for Android and iOS. The issue stems from the app’s handling of the ms-msa:// deep link used during onboarding, sign-in, and QR-code-based authentication flows. According to the provided reporting, Microsoft Authenticator did not properly claim or exclusively bind this URI scheme, allowing a malicious application installed on the same device to register itself as a handler for the same deep link. If a victim scanned a legitimate Microsoft QR code or tapped a sign-in link and the malicious app was selected to handle the link, the rogue app could intercept authentication data embedded in the deep link, including token or code parameters intended for Microsoft Authenticator. The intercepted data could then be exfiltrated and used to complete authentication flows for the victim’s Microsoft account.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
13 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A deep link hijacking vulnerability in Microsoft Authenticator where the ms-msa:// authentication link was not properly claimed by the app, allowing a malicious app to intercept authentication tokens and cause full account takeover.
A vulnerability in Microsoft Authenticator on Android and iOS that could allow a malicious app on the same device to intercept authentication deep links, one-time login codes, or sign-in data intended for the authenticator app.
A Microsoft Authenticator (Android/iOS) vulnerability that can enable a man-in-the-middle sign-in interception via a malicious app handling sign-in deep links (requires user interaction/social engineering).
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.