CVE-2026-32948: Scala.epfl Sbt RCE Vulnerability

CVE-2026-32948 Overview

CVE-2026-32948 is a command injection vulnerability affecting sbt (Simple Build Tool), a widely-used build tool for Scala, Java, and other programming languages. The vulnerability exists in versions 0.9.5 through 1.12.6 when running on Windows systems. The flaw allows attackers to execute arbitrary commands through malicious URI fragments in VCS (Version Control System) commands.

The vulnerability stems from how sbt invokes cmd /c to execute VCS commands such as git, hg, and svn on Windows. User-controlled URI fragments (specifying branches, tags, or revisions) are passed directly to these commands without proper validation or sanitization. Since the Windows command interpreter interprets characters like &, |, and ; as command separators, a maliciously crafted fragment can break out of the intended command context and execute arbitrary system commands.

Critical Impact
Attackers can execute arbitrary commands on Windows systems by injecting malicious payloads into VCS URI fragments in sbt build definitions, potentially leading to complete system compromise during build operations.

Affected Products

sbt versions 0.9.5 to 1.12.6 (prior to 1.12.7)
Microsoft Windows operating systems
Projects using sbt with VCS dependencies (git, hg, svn)

Discovery Timeline

March 24, 2026 - CVE-2026-32948 published to NVD
March 26, 2026 - Last updated in NVD database

Technical Details for CVE-2026-32948

Vulnerability Analysis

This command injection vulnerability (CWE-78: OS Command Injection) affects the sbt build tool's handling of VCS operations on Windows platforms. When sbt needs to fetch dependencies from version control repositories, it constructs shell commands using Process("cmd", "/c", ...) to invoke VCS tools like git, hg, or svn.

The URI fragment portion of repository URLs—which specifies branches, tags, or specific revisions—is directly controlled by the build definition author. Without proper input validation or escaping, these fragments are concatenated into command strings that are then executed by the Windows command interpreter.

The Windows cmd /c construct interprets several special characters as command separators, including:

& - Sequential command execution
| - Pipe output to another command
; - Command separator (in some contexts)

An attacker who can influence the build definition (either by contributing malicious code or through supply chain attacks) can craft URI fragments containing these metacharacters to execute arbitrary commands with the privileges of the user running the build.

Root Cause

The root cause is insufficient input validation of user-controlled URI fragments before they are passed to shell commands. The sbt codebase failed to sanitize or escape shell metacharacters in repository URL fragments, allowing command separator characters to be interpreted by cmd /c rather than being treated as literal strings.

This is a classic command injection pattern where untrusted input is concatenated into shell commands without proper escaping or the use of safer APIs that avoid shell interpretation entirely.

Attack Vector

The attack vector is local, requiring user interaction. An attacker must convince a developer or CI/CD system to build a project containing a malicious VCS dependency definition. The attack scenario typically involves:

A malicious actor creates or modifies a build definition (e.g., build.sbt) to include a VCS dependency with a crafted URI fragment
The URI fragment contains command injection payloads using shell metacharacters
When sbt resolves dependencies on a Windows system, it constructs and executes the VCS command
The Windows command interpreter parses the metacharacters, executing the injected commands

The malicious payload would be embedded in the URI fragment portion that normally specifies a branch, tag, or revision. For example, a fragment like main & malicious_command would cause the injected command to execute after the legitimate VCS operation.

Detection Methods for CVE-2026-32948

Indicators of Compromise

Unusual process spawning from sbt or Java processes on Windows systems during build operations
Unexpected cmd.exe child processes executing commands unrelated to version control operations
Suspicious VCS repository URLs containing shell metacharacters (&, |, ;) in URI fragments within build definition files
Anomalous network connections or file system modifications occurring during sbt dependency resolution

Detection Strategies

Monitor for cmd.exe processes spawned by sbt with command lines containing unusual characters or multiple command separators
Implement static analysis scanning of build.sbt and other sbt configuration files for suspicious VCS URI patterns
Review build logs for VCS dependency URLs containing shell metacharacters in the fragment portion
Enable process auditing on Windows build systems to capture command-line arguments for forensic analysis

Monitoring Recommendations

Configure endpoint detection to alert on chained command execution patterns originating from build tool processes
Implement file integrity monitoring on sbt build definition files to detect unauthorized modifications
Review CI/CD pipeline logs for dependency resolution operations involving unusual repository URLs
Monitor for execution of unexpected binaries during build operations on Windows systems

How to Mitigate CVE-2026-32948

Immediate Actions Required

Upgrade sbt to version 1.12.7 or later immediately on all Windows systems
Audit existing build definitions for VCS dependencies with suspicious URI fragments
Review recently added or modified VCS dependencies in project build files
Consider temporarily building on non-Windows platforms if upgrade is not immediately possible

Patch Information

The sbt maintainers have released version 1.12.7 which addresses this vulnerability. The fix implements proper input validation and sanitization of URI fragments before they are passed to VCS commands.

The patches are available at:

Additional information is available in the GitHub Security Advisory GHSA-x4ff-q6h8-v7gw and the sbt v1.12.7 Release Notes.

Workarounds

Run sbt builds on Linux or macOS systems where this vulnerability does not apply
Carefully review all VCS dependencies and URI fragments in build definitions before building
Implement build isolation using containers or sandboxed environments to limit potential impact
Restrict network access during builds to prevent data exfiltration if exploitation occurs

bash

# Upgrade sbt to the patched version
# Update sbt version in project/build.properties
echo "sbt.version=1.12.7" > project/build.properties

# Alternatively, update sbt launcher globally
# Download from https://github.com/sbt/sbt/releases/tag/v1.12.7