CVE-2026-29786
tar has Hardlink Path Traversal via Drive-Relative Linkpath
Executive Summary
CVE-2026-29786 is a high severity vulnerability affecting binary-analysis. It is classified as an undisclosed flaw. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"The fundamental weakness here is traced back to within ### Summary `tar` (npm), allowing a lack of rigorous type checking mechanisms. In a real-world scenario, an attacker could exploit this by compromise the entire application stack, rendering traditional defenses ineffective. The Precogs binary analysis module maps structural execution flows to harden the environment against lateral movement."
What is this vulnerability?
CVE-2026-29786 is categorized as a critical Memory Corruption Vulnerability flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.
Summary tar (npm) can be tricked into creating a hardlink that points outside the extraction directory by using a drive-relative link target such as .
This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.
Risk Assessment
| Metric | Value |
|---|---|
| CVSS Base Score | 7.5 (HIGH) |
| Vector String | N/A |
| Published | March 5, 2026 |
| Last Modified | March 10, 2026 |
| Related CWEs | N/A |
Impact on Systems
✅ Remote Code Execution: Adversaries may execute arbitrary code by overwriting memory regions.
✅ Denial of Service: Memory corruption often leads to unrecoverable application crashes.
✅ Information Disclosure: Out-of-bounds reads can expose adjacent memory containing sensitive data.
How to fix this issue?
Implement the following strategic mitigations immediately to eliminate the attack surface.
1. Memory-Safe Languages When possible, migrate parsing logic to memory-safe languages like Rust or Go.
2. Compiler Protections Ensure the binary is compiled with ASLR, DEP/NX, Stack Canaries, and RELRO.
3. Fuzz Testing Implement continuous fuzzing with AddressSanitizer (ASan) in the CI/CD pipeline.
Vulnerability Signature
// Generic Memory Corruption Vector (C/C++)
void process_input(char *user_data, size_t size) \{
char buffer[256];
// DANGEROUS: Unbounded memory operation
memcpy(buffer, user_data, size); // size may exceed 256
// SECURED: Bound-checked operation
if (size \> sizeof(buffer)) \{
size = sizeof(buffer);
\}
memcpy(buffer, user_data, size);
\}
References and Sources
Vulnerability Code Signature
Attack Data Flow
| Stage | Detail |
|---|---|
| Source | Network packet or file input |
| Vector | Data exceeds the allocated buffer bounds during a copy operation |
| Sink | strcpy(), memcpy(), or pointer arithmetic |
| Impact | Memory corruption, Remote Code Execution (RCE) |
Vulnerable Code Pattern
// ❌ VULNERABLE: Memory Corruption
void process_data(char *input) {
char buffer[128];
// Taint sink: copies without bounds checking
strcpy(buffer, input);
}
Secure Code Pattern
// ✅ SECURE: Bounded Memory Operations
void process_data(char *input) {
char buffer[128];
// Sanitized boundary check
strncpy(buffer, input, sizeof(buffer) - 1);
buffer[sizeof(buffer) - 1] = '\0';
}
How Precogs Detects This
Precogs Binary SAST engine explicitly uncovers memory boundary violations and unsafe memory management functions in compiled binaries.\n