EUVD-2026-44318
GHSA-rwpj-48r2-w395
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
Network-reachable AD FS endpoint (AV:N) exploitable with an authenticated low-privilege session (PR:L) and no user interaction; out-of-bounds read discloses sensitive memory (C:H) with possible service instability (A:L), no integrity impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Out-of-bounds read in Active Directory Federation Services (AD FS) allows an authorized attacker to disclose information over a network.
AnalysisAI
Information disclosure in Microsoft Active Directory Federation Services (AD FS) lets an authenticated, network-based attacker read memory outside intended bounds and leak sensitive data, per Microsoft's own report of the flaw (tracked in MSRC as CVE-2026-58529). The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N, C:H) indicates low-privilege remote exploitation with high confidentiality impact; there is no public exploit identified at time of analysis and it is not on CISA KEV. A vendor patch is available. Note a data discrepancy: the flaw is described as AD FS (a server role) yet the only CPE lists the Windows 11 version 26H1 client - verify affected platforms with Microsoft.
Technical ContextAI
AD FS is Microsoft's on-premises identity federation service that issues security tokens (SAML/WS-Federation/OAuth) to enable single sign-on between an organization's Active Directory and external/relying-party applications, typically exposed over HTTPS network endpoints. The root cause is CWE-125, an out-of-bounds read, where code reads memory past the end (or before the start) of an allocated buffer - here likely during parsing of attacker-influenced request/token data - returning adjacent process memory contents. Microsoft's tagging also references 'Buffer Overflow,' consistent with a boundary-checking defect in a parser. Because AD FS handles authentication material, leaked memory could plausibly expose tokens, keys, or other secrets, which aligns with the C:H rating.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-58529 as listed in the MSRC update guide (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58529); the input confirms a fix is available but does not enumerate an exact patched build number, so pull the specific KB/version from that advisory for your platform. Because exploitation requires an authenticated (PR:L) network position, interim compensating controls include restricting network reachability of AD FS endpoints (for example, placing the AD FS/WAP proxy behind conditional access and limiting exposure of the federation and token endpoints to trusted networks or VPN), enforcing least-privilege on accounts that can authenticate to AD FS, and increasing monitoring of AD FS request/audit logs for anomalous access - with the trade-off that tightening endpoint exposure can disrupt legitimate external federation/SSO for remote users. These controls reduce but do not eliminate risk; patching is the only complete fix.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today