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Shescape CVE-2026-73055

CRITICAL
Improper Encoding or Escaping of Output (CWE-116)
2026-08-15 disclosure@vulncheck.com
9.3
CVSS 4.0 · Vendor: vulncheck
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Vendor (vulncheck) PRIMARY
9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
4.8 MEDIUM

Untrusted input may arrive over the network (AV:N) but exploitation needs a non-default BusyBox sh assignment context (AC:H); impact is home-directory disclosure (C:L) and possible command-target change (I:L), no availability effect.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (vulncheck).

CVSS VectorVendor: vulncheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Aug 15, 2026 - 22:36 vuln.today
Analysis Generated
Aug 15, 2026 - 22:36 vuln.today
CVE Published
Aug 15, 2026 - 22:16 cve.org
CRITICAL 9.3

DescriptionCVE.org

Shescape before 2.1.15 (and 3.0.0 before 3.0.2) fails to properly escape tilde (~) characters in assignment contexts on Unix systems where the shell is explicitly configured to "sh" or true and /bin/sh points to BusyBox. Using the escape and escapeAll APIs with untrusted input in an assignment prefixed to a command, an attacker can inject a tilde payload to disclose the user's home directory location and, depending on usage, alter the location on which a command operates.

AnalysisAI

Information disclosure in Shescape, a Node.js shell-argument escaping library, affects versions before 2.1.15 and the 3.0.x line before 3.0.2 when the library's escape/escapeAll output is placed in a shell variable assignment and the runtime shell is explicitly set to "sh" (or true) with /bin/sh symlinked to BusyBox. Under those conditions an attacker who controls the escaped input can inject an unescaped tilde (~) that BusyBox expands, revealing the user's home directory path and, depending on how the assignment feeds the command, redirecting the filesystem location a command targets. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Supply tilde-prefixed untrusted input
Exploit
Passed through escape/escapeAll in assignment prefix
Execution
BusyBox sh expands unescaped ~
Impact
Disclose home directory / redirect command target

Vulnerability AssessmentAI

Exploitation Exploitation requires all of the following concrete prerequisites drawn from the description: the target uses Shescape's escape or escapeAll API on attacker-controlled input; that output is placed as a variable-assignment prefix to a command (VAR=value command form); the runtime shell is explicitly configured to "sh" or true; and the host's /bin/sh symlink points to BusyBox on a Unix system. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The supplied CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H, score 9.3) substantially overstates real-world impact and conflicts with the description, which characterizes the issue as disclosure of the home directory location and possible alteration of a command's target location - an information-disclosure/limited-integrity problem, not full confidentiality, integrity, and availability compromise. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An application running on a BusyBox-based container (a very common Alpine/embedded setup) uses Shescape's escapeAll to build a command like ENVVAR=<user-supplied-path> some-tool, with the shell set to sh. An attacker submits a value beginning with ~ that survives escaping and is expanded by BusyBox to the process owner's home directory, leaking that path back to the attacker or causing the tool to operate on a different filesystem location than intended. …
Remediation Upgrade Shescape to a fixed release: 2.1.15 for the 2.x line or 3.0.2 for the 3.x line (Vendor-released patch: 2.1.15 and 3.0.2), which include the corrected tilde escaping from PR #2678 (commits 7cba30594c16a21524706efe2f6c6c9d8923f411 and d86bf2ae22961c73458bddf70dd06adf9dadb36c); consult GHSA-j44h-fqhh-fh28 for guidance. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, audit all Node.js applications to identify those using Shescape versions prior to 2.1.15 (2.x line) or 3.0.2 (3.x line) by reviewing package-lock.json and dependency manifests; prioritize systems running containerized workloads or embedded Linux environments using BusyBox. …

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CVE-2026-73055 vulnerability details – vuln.today

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