CVE-2026-88113

Executive Summary

CVE-2026-88113 is a use-after-free (CWE-416) vulnerability in the Windows Broadcast DVR User Service, a Windows component associated with the Broadcast DVR / digital video recording subsystem. An attacker who already holds a low-privileged local account can trigger the flaw to elevate privileges to SYSTEM-level integrity on the affected host, with full compromise of confidentiality, integrity, and availability (CVSS 3.1 base 7.0). Because exploitation requires local access (AV:L) and a high degree of attack complexity (AC:H), the vulnerability is most relevant to post-compromise privilege escalation, insider abuse, and local persistence chains rather than remote mass exploitation. No public proof-of-concept, exploit code, or Nuclei template is currently available, and the vulnerability has not been added to CISA KEV.

Technical Analysis

CVE-2026-88113 is classified under CWE-416, Use After Free. The NVD description states the defect resides in the Windows Broadcast DVR User Service and that successful exploitation "allows an authorized attacker to elevate privileges locally."

A use-after-free condition arises when an application continues to reference a heap (or pool) memory object after that object has been freed and its memory potentially reallocated for a different purpose. In the Windows kernel and privileged service context, this class of bug typically manifests in one of the following ways:

• A pointer to a freed object is dereferenced by the service (a stale read), potentially leaking kernel or service memory.
• A freed object is written to after reclamation (a stale write), allowing an attacker to corrupt data structures that the service subsequently operates on.
• The freed slot is reallocated under attacker influence, so the dangling pointer now resolves to attacker-controlled content that the service treats as trusted.

The Windows Broadcast DVR User Service is a privileged Windows service, and the defining property of this CVE is that the vulnerable code path is reachable from a local, non-administrative context. The CVSS vector indicates PR:L (low privileges required) and UI:N (no user interaction), meaning the attacker does not need to trick an interactive user but must already be able to execute code or issue requests against the service on the target machine.

The high attack-complexity rating (AC:H) is consistent with a use-after-free that requires precise timing or heap-shaping to turn a memory-safety error into a reliable elevation-of-privilege primitive. Reliable exploitation of UAF conditions generally demands careful grooming of the target allocator to place a controlled object in the reclaimed slot, then steering a privileged operation through the dangling reference. The description does not disclose the specific object, allocation size, or code path involved, and no further code-level detail is available from the provided intelligence; this report therefore confines itself to the vulnerability class and the observable attack surface rather than inventing implementation specifics.

Attack surface: the Windows Broadcast DVR User Service is intended to serve the local user context, but its privileged execution means any memory-safety failure within that trust boundary becomes a privilege boundary crossing. The attacker's objective is to convert a non-administrative foothold into SYSTEM-equivalent execution.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template exists for CVE-2026-88113. The following attack chain is therefore inferred strictly from the vulnerability class (use-after-free in a privileged Windows service reachable by a low-privileged local user) and the CVSS vector. No specific internal function names, API parameters, or memory offsets are asserted, because none are provided in the available data.

1) Reconnaissance / target identification The attacker requires local code execution or an interactive session with at least low privileges on a Windows host. The attacker identifies that the Windows Broadcast DVR User Service is present and running. Because the exploit is local-only (AV:L), internet-facing scanning is not applicable; the attacker is already positioned on the endpoint — a compromised user workstation, a VDI session, a jump host, or any environment reachable after an initial access phase. The attacker enumerates locally running services and verifies the target service is active and reachable from the current privilege level.

2) Triggering the flaw (use-after-free class) The attacker issues operations through the service's normal client interface (for example, IPC, RPC, or a documented service control surface) to drive the vulnerable code path. In a UAF of this class, the attacker manipulates object lifecycle: inducing the service to free an internal object and then causing it to operate on the stale reference. Because exploitation complexity is rated high, the attacker typically must interleave operations, repeatedly trigger allocation/free cycles, or spray the service's heap so the freed slot is reclaimed by an object the attacker can influence. The precise sequence is not documented in the available data.

3) Payload / execution at the vulnerability-class level Reliable UAF exploitation typically proceeds from the dangling pointer to memory corruption: the attacker arranges for attacker-influenced data to occupy the reallocated memory, so that when the privileged service dereferences the stale pointer, it reads or writes data of the attacker's choosing. In a kernel or SYSTEM-context service, this can corrupt a structure the service later acts on, redirecting execution or enabling arbitrary memory write. The attacker then leverages this to run code at SYSTEM integrity. No public exploit details are available; the exact payload mechanism is theoretical until a PoC or advisory provides specifics.

4) Post-exploitation impact On success, the attacker elevates from a low-privileged local account to SYSTEM-equivalent privilege on the endpoint. This is a full local compromise: the attacker can disable defenses, install persistent services or scheduled tasks, dump credentials, move laterally within the Windows domain, and access data protected from the normal user. Because exploitation results in high confidentiality, integrity, and availability impact, a successful attacker effectively owns the host and any credentials or trust material resident on it.

Impact Assessment

• Confidentiality (C:H): SYSTEM-level access exposes all data on the host, including memory-resident secrets, credentials, and protected user or system files.
• Integrity (I:H): The attacker can modify system binaries, configuration, and security controls at the highest local privilege level.
• Availability (A:H): Privileged code execution and potential manipulation of system services can render the host unstable or unavailable, whether intentionally or as a side effect of memory corruption.
• Attack vector (AV:L): Exploitation requires local access; remote reach is limited to environments where the attacker has already obtained a foothold.
• Attack complexity (AC:H): The UAF must be groomed into a reliable primitive; success is not trivial, which reduces mass-exploitation risk but not post-compromise risk.
• Privileges required (PR:L) / User interaction (UI:N): Any low-privileged local account is sufficient and no victim interaction is required, widening the set of viable attackers once on-host.

Blast radius: Per-endpoint compromise that escalates to domain-level risk wherever the host holds cached credentials, delegated tokens, or administrative sessions. Because the target is a built-in Windows service, exposure is broad across affected Windows installations, but no affected version range could be confirmed from the available data. Enterprises without a confirmed patch window should treat all Windows endpoints running this service as potentially affected until version-specific guidance is issued.

Detection Guidance

Detection strategy for a local use-after-free privilege-escalation in a Windows service centers on abnormal service interactions by non-administrative processes, unexpected child-process lineage from privileged Windows services, post-exploitation artifacts (service creation, token theft, credential dumping), and crash telemetry that may indicate exploitation attempts.

Sigma Rule

title: Potential Privilege Escalation via Windows Broadcast DVR User Service (CVE-2026-88113)
id: 3b2f6c1a-9d47-4e8b-b6c2-88113a0c0001
status: experimental
description: Detects anomalous process activity consistent with local privilege escalation following a use-after-free in the Windows Broadcast DVR User Service.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-88113
author: valtersit.com Threat Intelligence
date: 2026/01/01
tags:
  - attack.privilege-escalation
  - attack.t1068
  - cve.2026-88113
logsource:
  product: windows
  category: process_creation
detection:
  selection_susp_parent:
    ParentImage|endswith:
      - '\svchost.exe'
      - '\services.exe'
    Image|endswith:
      - '\cmd.exe'
      - '\powershell.exe'
      - '\pwsh.exe'
      - '\wscript.exe'
      - '\cscript.exe'
      - '\rundll32.exe'
  selection_cmdline:
    CommandLine|contains:
      - 'whoami'
      - 'net localgroup administrators'
      - 'reg save HKLM'
      - 'lsass'
  filter_known:
    Image|endswith: '\sppsvc.exe'
  condition: selection_susp_parent and selection_cmdline and not filter_known
falsepositives:
  - Legitimate administrative automation triggered from system services
level: high

YARA Rule

rule CVE_2026_88113_UAF_Exploit_Artifacts
{
    meta:
        description = "Heuristic detection of local privilege-escalation exploit artifacts targeting a Windows use-after-free (CVE-2026-88113)"
        author = "valtersit.com Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-88113"
        date = "2026-01-01"
        severity = "high"

    strings:
        $cve = "CVE-2026-88113" ascii wide nocase
        $svc1 = "Broadcast DVR User Service" ascii wide nocase
        $svc2 = "BroadcastDVR" ascii wide nocase
        $uaf  = "use after free" ascii wide nocase
        $eop  = "SeDebugPrivilege" ascii wide
        $heap = "RtlAllocateHeap" ascii wide
        $hspray = "HeapCreate" ascii wide

    condition:
        (uint16(0) == 0x5A4D) and
        (
            $cve or
            (1 of ($svc*)) or
            ($uaf and any of ($eop, $heap, $hspray))
        )
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-88113 Potential Windows Broadcast DVR User Service UAF EoP Indicator"; flow:established,to_server; content:"BroadcastDVR"; nocase; content:"|5c|"; nocase; distance:0; classtype:attempted-admin; reference:cve,2026-88113; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-88113; sid:202688113; rev:1; metadata:created_at 2026_01_01, updated_at 2026_01_01, confidence Low;)

Note: this is a local privilege-escalation vulnerability; network signature coverage is inherently limited and intended only as a coarse indicator of lateral or staged activity involving the target service.

Elastic Detection

process where event.type == "start" and
  process.parent.executable != null and
  process.parent.name in ("svchost.exe", "services.exe") and
  process.name in ("cmd.exe", "powershell.exe", "pwsh.exe", "rundll32.exe", "reg.exe") and
  (
    process.command_line : ("*whoami*", "*net localgroup administrators*", "*reg save HKLM*", "*lsass*")
  )

Splunk SPL Query

index=windows (sourcetype=WinEventLog:Security OR sourcetype=WinEventLog:Sysmon)
(EventCode=1 OR EventID=1)
| search parent_process_name IN ("svchost.exe","services.exe")
| search process_name IN ("cmd.exe","powershell.exe","pwsh.exe","rundll32.exe","reg.exe")
| search (CommandLine="*whoami*" OR CommandLine="*net localgroup administrators*" OR CommandLine="*reg save HKLM*" OR CommandLine="*lsass*")
| stats count min(_time) as first_seen max(_time) as last_seen by host, user, parent_process_name, process_name, CommandLine
| where count > 0
| sort - first_seen

Wazuh OSSEC Rule

<group name="windows,cve-2026-88113,privilege_escalation,">
  <rule id="100113" level="12">
    <if_sid>60000</if_sid>
    <field name="win.eventdata.parentImage">svchost.exe|services.exe</field>
    <field name="win.eventdata.image">cmd.exe|powershell.exe|pwsh.exe|rundll32.exe|reg.exe</field>
    <field name="win.eventdata.commandLine">whoami|net localgroup administrators|reg save HKLM|lsass</field>
    <description>CVE-2026-88113: Suspicious privileged child process consistent with local elevation of privilege via Windows Broadcast DVR User Service</description>
    <mitre>
      <id>T1068</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch evidence exists from any tracked source; no vendor fix or workaround is currently available.

1) Immediate mitigations

• Apply the principle of least privilege: reduce the number of endpoints where unprivileged users can execute code or interact with local services. Because exploitation requires a pre-existing low-privileged local foothold (PR:L, AV:L), hardening initial access is the highest-leverage control.
• Restrict interactive logon and local execution on high-value systems (domain controllers, jump hosts, administrative workstations) to trusted administrative accounts only.
• Where operationally feasible, disable or restrict the Windows Broadcast DVR User Service on hosts that do not require DVR functionality, reducing the available attack surface. Validate application dependencies before disabling any built-in service.
• Enable Credential Guard and LSA protection to contain the value of any successful SYSTEM-level compromise.
• Enforce application allowlisting to prevent unauthorized binaries from executing in the user context; monitor for anomalous process lineage from privileged services.

2) Patch / upgrade steps

• No vendor patch is currently referenced. Monitor the Microsoft Security Update Guide and Microsoft Security Response Center advisories for a fix keyed to CVE-2026-88113.
• Once a patch is published, treat it as priority for affected Windows versions; validate the mapping of affected builds to the fixed build in the vendor advisory before declaring remediation complete.
• Maintain an accurate software inventory so affected hosts can be rapidly identified and patched when version-specific guidance becomes available.

3) Long-term hardening

• Adopt a threat-informed defense posture for local privilege escalation: continuously monitor use-after-free and memory-corruption classes in privileged Windows services, as these frequently emerge post-patch as n-day escalation vectors.
• Subscribe to CISA KEV and vendor advisories; because this CVE is not in KEV, prioritization must be driven by internal exposure and the value of the local foothold rather than by observed exploitation.
• Segment and monitor endpoints so that a successful local elevation on one host does not immediately translate into domain-wide control (tiered administrative model, protected users group, privileged access workstations).

References

1. National Vulnerability Database — CVE-2026-88113: https://nvd.nist.gov/vuln/detail/CVE-2026-88113
2. MITRE CWE-416 — Use After Free: https://cwe.mitre.org/data/definitions/416.html
3. MITRE ATT&CK T1068 — Exploitation for Privilege Escalation: https://attack.mitre.org/techniques/T1068/
4. Microsoft Security Update Guide (monitor for the CVE-2026-88113 fix): https://msrc.microsoft.com/update-guide
5. CISA Known Exploited Vulnerabilities Catalog (CVE-2026-88113 not currently listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Threat actor and in-the-wild evidence: None available. CVE-2026-88113 is not listed in CISA KEV, and there is no public proof-of-concept, exploit code, or Nuclei template. EPSS score is 0.00204 (9.7th percentile), indicating a low near-term probability of exploitation. All exploitation analysis in this report is derived from the vulnerability class and the published CVSS vector, not from observed attack activity.