Security readout for executives and security teams
Plain-English summary
A flawed third-party fax-modem driver (Agere ltmdm64.sys) shipped inside Windows for years. A logged-in user could abuse it to gain administrator-level control of the machine. Microsoft fixed this by removing the driver in the October 2025 update; old fax-modem hardware that relied on it will stop working. Attackers are already exploiting it, so patching is urgent.
Executive priority
Treat as urgent on Windows fleets. Apply October 2025 cumulative updates promptly and accept that legacy fax-modem hardware tied to ltmdm64.sys will stop working.
Technical view
CVE-2025-24990 is an elevation-of-privilege flaw (CWE-822, untrusted pointer dereference) in the Agere Modem driver ltmdm64.sys, which Microsoft shipped natively in Windows. CVSS 3.1 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). A local low-privileged user can leverage the kernel driver to obtain SYSTEM. Microsoft's October 2025 cumulative update removes the driver entirely; no patched version is offered.
Likely exposure
Broad: the vulnerable Agere Modem driver shipped natively across nearly all supported Windows client and server versions, from Windows Server 2008 SP2 through Windows 11 25H2. Any unpatched endpoint or server where the driver remains loaded is exposed to a local attacker with standard user access.
Exploitation context
CISA lists this CVE in the Known Exploited Vulnerabilities catalog, indicating confirmed in-the-wild exploitation. The CVSS temporal vector (E:F/RL:O/RC:C) reflects functional exploit code and an official remediation. Attack is local with low privileges required and no user interaction.
Researcher notes
CWE-822 (untrusted pointer dereference) in a kernel-mode driver yields SYSTEM-level elevation from a low-privileged local context. CVSS 7.8 with E:F/RL:O/RC:C and KEV listing means working exploitation exists. Microsoft's remediation is driver removal rather than a fix, so post-patch the attack surface is eliminated; verify ltmdm64.sys is absent and ensure no rollback or sideloaded copy persists. Coverage spans legacy SKUs (Server 2008/2008 R2, 2012/R2) where patch latency is historically higher.
Mitigation direction
- Install the October 2025 Windows cumulative update that removes ltmdm64.sys on all client and server SKUs.
- Inventory and retire any fax-modem workflows that depend on the Agere driver before patching.
- Restrict local logon and limit standard-user code execution on systems pending the update.
- Follow Microsoft MSRC guidance for CVE-2025-24990 when planning rollout windows.
- Prioritize internet-facing, multi-user, and shared workstations where local privilege escalation has highest impact.
Validation and detection
- Confirm the October 2025 (or later) cumulative update is installed on every Windows client and server.
- Verify ltmdm64.sys is no longer present in %SystemRoot%\System32\drivers after patching.
- Check CISA KEV due-date compliance for federal or contractually bound systems.
- Audit endpoint management for any policy that re-stages or sideloads the legacy driver.
- Review EDR telemetry for prior local privilege-escalation indicators on long-unpatched hosts.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-822: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2025-24990 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- Windows Agere Modem Driver Elevation of Privilege VulnerabilityCVE reference · vendor-advisory, patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-24990CVE reference · government-resource
- https://www.vicarius.io/vsociety/posts/cve-2025-24990-detection-script-elevation-of-privilege-vulnerability-in-agere-modem-driver-affecting-windowsCVE reference
- https://www.vicarius.io/vsociety/posts/cve-2025-24990-mitigation-script-elevation-of-privilege-vulnerability-in-agere-modem-driver-affecting-windowsCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Untrusted Pointer Dereference
Untrusted Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.