CVE-2026-34451

Description

Claude SDK for TypeScript provides access to the Claude API from server-side TypeScript or JavaScript applications. From version 0.79.0 to before version 0.81.0, the local filesystem memory tool in the Anthropic TypeScript SDK validated model-supplied paths using a string prefix check that did not append a trailing path separator. A model steered by prompt injection could supply a crafted path that resolved to a sibling directory sharing the memory root's name as a prefix, allowing reads and writes outside the sandboxed memory directory. This issue has been patched in version 0.81.0.

CVSS Details

CVSS Score

5.4

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

Configurations (Affected Products)

cpe:2.3:a:anthropic:claude_sdk_for_typescript:*:*:*:*:*:*:*:* - VULNERABLE

Anthropic TypeScript SDK >= 0.79.0, < 0.81.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// Conceptual PoC demonstrating the bypass logic
const MEMORY_ROOT = '/var/sandbox/memory';

// Vulnerable validation logic (simplified)
function isPathValid(path) {
    // Vulnerability: Checks prefix without ensuring trailing separator
    return path.startsWith(MEMORY_ROOT);
}

// Exploit scenario: Attacker injects prompt to access sibling directory
const maliciousPath = '/var/sandbox/memorystore'; // Note: starts with MEMORY_ROOT prefix

if (isPathValid(maliciousPath)) {
    console.log(`[+] Access granted to: ${maliciousPath}`);
    // In the real scenario, the SDK would read/write here
} else {
    console.log('[-] Access denied');
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-34451
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-34451
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-34451/
[4] VulDB https://vuldb.com/cve/CVE-2026-34451
[5] https://github.com/anthropics/anthropic-sdk-typescript/commit/0ac69b3438ee9c96b21a7d3c39c07b7cdb6995d9
[6] https://github.com/anthropics/anthropic-sdk-typescript/releases/tag/sdk-v0.81.0
[7] https://github.com/anthropics/anthropic-sdk-typescript/security/advisories/GHSA-5474-4w2j-mq4c

Raw JSON Data

JSON

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