CVE-2026-54124: Windows Terminal RCE Vulnerability

CVE-2026-54124 Overview

CVE-2026-54124 is a local code execution vulnerability in Microsoft Windows Terminal caused by an integer overflow or wraparound condition [CWE-122]. The flaw allows an unauthorized attacker to execute arbitrary code on an affected system when a user is convinced to interact with crafted content processed by Windows Terminal. Microsoft published the advisory on July 14, 2026 and assigned a CVSS 3.1 base score of 7.8 with a CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H vector. Successful exploitation compromises the confidentiality, integrity, and availability of the affected host.

Critical Impact
A local attacker can execute arbitrary code with the privileges of the user running Windows Terminal, enabling full compromise of user data and installed applications.

Affected Products

Microsoft Windows Terminal (see the Microsoft Security Update Guide for specific affected builds)

Discovery Timeline

2026-07-14 - Microsoft publishes advisory for CVE-2026-54124
2026-07-14 - CVE-2026-54124 published to NVD
2026-07-16 - Last updated in NVD database

Technical Details for CVE-2026-54124

Vulnerability Analysis

CVE-2026-54124 is an integer overflow or wraparound vulnerability in Windows Terminal, categorized under [CWE-122] (Heap-based Buffer Overflow). Integer overflow conditions occur when an arithmetic operation produces a value outside the representable range of the target integer type. When such a value is subsequently used to compute a buffer size or index, the undersized allocation or wrapped index leads to memory corruption on the heap.

Exploitation requires local access and user interaction, consistent with the AV:L and UI:R components of the CVSS vector. The attack typically involves the user opening or processing attacker-supplied content inside Windows Terminal, such as a crafted file, escape sequence, or terminal input stream. No prior authentication is needed to stage the attack payload.

If successful, the attacker gains code execution in the security context of the current user. Microsoft has not disclosed the specific affected function or code path beyond the advisory. Refer to the Microsoft Security Update Guide entry for CVE-2026-54124 for authoritative technical details.

Root Cause

The root cause is an unchecked arithmetic operation whose result wraps around, producing an incorrect length or offset used in a subsequent memory operation. The heap-based nature of the overflow ([CWE-122]) indicates that dynamically allocated memory is corrupted, which can be leveraged to overwrite adjacent heap metadata or object pointers.

Attack Vector

The attack vector is local. An attacker crafts input processed by Windows Terminal and delivers it to a target user through means such as a malicious file, a link that spawns terminal content, or a payload injected into a shared terminal session. The user must interact with the crafted content for the overflow to trigger, after which the attacker's code runs with the user's privileges.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS score at time of publication is approximately 0.44%.

Detection Methods for CVE-2026-54124

Indicators of Compromise

Unexpected child processes spawned by WindowsTerminal.exe or OpenConsole.exe, particularly command interpreters (cmd.exe, powershell.exe) or script hosts launched with unusual arguments.
Crash events or Windows Error Reporting entries referencing Windows Terminal binaries with heap corruption exception codes such as 0xC0000374 or 0xC0000005.
Newly written executables or scripts in user-writable paths shortly after Windows Terminal opens attacker-supplied content.

Detection Strategies

Monitor process ancestry to flag any non-standard process created by Windows Terminal, correlating with recent file open or clipboard events.
Alert on Windows Terminal crashes followed by process creation from the same user session within a short time window, which may indicate exploitation attempts.
Inspect files delivered via email, chat, or download that reference terminal profiles, .wt configurations, or crafted escape sequences.

Monitoring Recommendations

Enable Sysmon Event IDs 1 (process create), 11 (file create), and 15 (file stream create) with rules scoped to Windows Terminal binaries.
Forward Windows Error Reporting and Application event logs to a centralized SIEM to detect repeated Windows Terminal faults across the fleet.
Track patch state for Windows Terminal across managed endpoints and alert on hosts still running vulnerable builds after the patch deadline.

How to Mitigate CVE-2026-54124

Immediate Actions Required

Apply the Microsoft security update for Windows Terminal referenced in the MSRC advisory for CVE-2026-54124 as soon as it is available in your update channel.
Inventory endpoints running Windows Terminal and prioritize patching for developer, administrator, and privileged-user workstations.
Instruct users to avoid opening untrusted files, links, or terminal payloads originating from unverified sources.

Patch Information

Microsoft is the authoritative source for patch guidance. Consult the Microsoft Security Update Guide entry for CVE-2026-54124 for the fixed Windows Terminal versions and deployment instructions. Windows Terminal updates are distributed through the Microsoft Store and via manual package installation for offline environments.

Workarounds

Restrict use of Windows Terminal on high-value systems until the patch is deployed, favoring the legacy Windows Console Host where operationally acceptable.
Apply application control policies (Windows Defender Application Control, AppLocker) to constrain the processes Windows Terminal can spawn.
Enforce least privilege so that any exploitation is confined to a low-privilege user context, limiting downstream impact.

bash

# Verify installed Windows Terminal version and update via winget
winget list --id Microsoft.WindowsTerminal
winget upgrade --id Microsoft.WindowsTerminal --exact --accept-source-agreements --accept-package-agreements