Improper access control in Microsoft Edge for Android allows an unauthorized attacker to bypass a security feature over a network.

Microsoft Edge for Android Information Disclosure Vulnerability

Absolute path traversal in Microsoft Edge for Android allows an unauthorized attacker to disclose information locally.

By holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would allow them to prompt the user to install an extension. Combined with user confusion, this could result in an unintended or malicious extension being installed.

A side-channel flaw was found in NSS, in the way P-384 and P-521 curves are used in the generation of EDSA signatures, leaking partial information about the ECDSA nonce. Given a small number of ECDSA signatures, this information can be used to steal the private key. The highest threat from this vulnerability is to data confidentiality.

A flaw was found in nss. Using the EM side-channel, it is possible to extract the position of zero and non-zero wNAF digits while nss-certutil tool performs scalar multiplication during the ECDSA signature generation, leaking partial information about the ECDSA nonce. Given a small number of ECDSA signatures, this information can be used to steal the private key. The highest threat from this vulnerability is to data confidentiality.

A flaw was found in nss. Using the EM side-channel, it is possible to extract the position of zero and non-zero wNAF digits while nss-certutil tool performs scalar multiplication during the ECDSA signature generation, leaking partial information about the ECDSA nonce. Given a small number of ECDSA signatures, this information can be used to steal the private key. The highest threat from this vulnerability is to data confidentiality.

When trying to load a non-video in an audio/video context the exact status code (200, 302, 404, 500, 412, 403, etc.) was disclosed via the MediaError Message. This level of information leakage is inconsistent with the standardized onerror/onsuccess disclosure and can lead to inferring login status to services or device discovery on a local network among other attacks.

A lock was missing when accessing a data structure and importing certificate information into the trust database.

If the Remote Debugging via USB feature was enabled in Firefox for Android on an Android version prior to Android 6.0, untrusted apps could have connected to the feature and operated with the privileges of the browser to read and interact with web content. The feature was implemented as a unix domain socket, protected by the Android SELinux policy; however, SELinux was not enforced for versions prior to 6.0. This was fixed by removing the Remote Debugging via USB feature from affected devices. Note: This issue only affected Firefox for Android. Other operating systems are unaffected.. This vulnerability affects Firefox < 83.

A website could have obscured the fullscreen notification by using a combination of <code>window.open</code>, fullscreen requests, <code>window.name</code> assignments, and <code>setInterval</code> calls. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 112, Focus for Android < 112, Firefox ESR < 102.10, Firefox for Android < 112, and Thunderbird < 102.10.

Following a Garbage Collector compaction, weak maps may have been accessed before they were correctly traced. This resulted in memory corruption and a potentially exploitable crash.

Last updated 24 July 2024

Last updated 24 July 2024

If multiple instances of resource exhaustion occurred at the incorrect time, the garbage collector could have caused memory corruption and a potentially exploitable crash.

When recording the screen while in Private Browsing on Firefox for Android the address bar and keyboard were not hidden, potentially leaking sensitive information.

This bug only affects Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox for Android < 112 and Focus for Android < 112.

A wrong lowering instruction in the ARM64 Ion compiler resulted in a wrong optimization result.

Last updated 24 July 2024

Inappropriate implementation in CORS in Google Chrome prior to 151.0.7922.169 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: High)

Incorrect reference resolution in Core in Google Chrome on on Android prior to 151.0.7922.169 allowed a remote attacker leveraging social engineering to obtain sensitive information via a crafted HTML page. (Chromium security severity: High)

Information leak in Skia in Google Chrome prior to 151.0.7922.169 allowed a remote attacker to potentially bypass web origin policy via a crafted HTML page. (Chromium security severity: High)

An authentication bypass vulnerability in the network driver of Palo Alto Networks Prisma® Access Agent on Windows enables a local administrator to bypass security inspection, subsequently allowing them to inject and intercept arbitrary network traffic.

The Prisma Access Agent on Linux, macOS, iOS, Android, and Chrome OS is not affected.

An improper link resolution before file access vulnerability exists in the Palo Alto Networks Prisma® Access Agent on Linux platforms that enables a local low privileged user to delete system files in a limited scope and disable Prisma Access Agent.

The Prisma Access Agent on macOS, Windows, iOS, Android, and Chrome OS is not affected.

Summary

I originally reported this through Google Bug Hunters. The Google Bug Hunters team said this is in OSS VRP scope but not reward-eligible due to the project tier, and asked me to file an issue or PR directly with this repository. I am reporting it privately here first because it is an unfixed security issue.

McpContext.validatePath() enforces workspace roots by checking whether path.resolve(filePath) textually falls under one of the configured root paths. path.resolve() does not canonicalize symbolic links. As a result, a symlink inside a configured workspace root can point to a file outside that root, pass validation, and then be followed by downstream file read/write operations.

This bypass applies even when the MCP client correctly declares the roots capability with a non-empty list. It is separate from the documented legacy behavior where missing roots capability allows all paths.

The practical impact is a workspace-boundary bypass. In the write direction, filePath-writing tools can overwrite out-of-root files through an in-root symlink. In the read direction, uploadfile can read through the symlink and send the file to the currently selected web page.

Details

Affected code:

src/McpContext.ts:178-199

ts validatePath(filePath?: string): void { if (filePath === undefined) { return; } const roots = this.roots(); if (roots === undefined) { return; } const absolutePath = path.resolve(filePath); for (const root of roots) { const rootPath = path.resolve(fileURLToPath(root.uri)); if ( absolutePath === rootPath || absolutePath.startsWith(rootPath + path.sep) ) { return; } } throw new Error( Access denied: path ${filePath} is not within any of the workspace roots ${JSON.stringify(roots)}., ); }

path.resolve() only normalizes path text such as . and ... It does not call realpath() and does not resolve symlinks. Therefore, a path like:

text /workspace/project/cache/profile

can textually pass the /workspace prefix check even when cache/profile is a symlink to:

text /home/user/.aws/credentials

Downstream consumers then perform real filesystem operations without ONOFOLLOW:

- src/McpContext.ts:720-738 saveFile() uses fs.mkdir({recursive: true}) and fs.writeFile(). - src/tools/input.ts:454-497 uploadfile calls puppeteer.uploadFile(filePath) or fileChooser.accept([filePath]). - Other filePath-writing tools include screenshots, heap snapshots, network response save paths, snapshots, screencasts, Lighthouse output, and performance trace saves.

This is not a TOCTOU/race condition. The symlink exists before validation and the PoC uses a single process. The issue is a canonicalization bypass / improper link resolution.

Preconditions:

- The MCP client declares roots and supplies at least one workspace root. - A symlink exists inside the workspace and points outside the workspace. - For the remote prompt-injection chain, the user processes untrusted page content while chrome-devtools-mcp is connected.

A remote attacker does not need local access if a suitable workspace-internal symlink already exists, or if another trusted tool/workflow can create it. Without such a symlink, the issue is a local/workspace-state-dependent boundary bypass.

PoC

Conceptual exploitation with a configured root:

text Configured roots: file:///workspace

Workspace path: /workspace/project/cache/profile -> /home/user/.aws/credentials

Tool call: uploadfile({ filePath: "/workspace/project/cache/profile", uid: "<file input element on current page>" })

Result: validatePath() accepts the path because it textually starts with /workspace. Puppeteer follows the symlink and uploads the target file to the page.

Lab-only PoC that replicates the exact validation logic and subsequent write. It writes only inside a fresh temporary directory and touches no system paths:

js const path = require('node:path'); const fs = require('node:fs'); const os = require('node:os'); const {pathToFileURL, fileURLToPath} = require('node:url');

const lab = fs.mkdtempSync(path.join(os.tmpdir(), 'cdtmcp-lab-'));

try { fs.chmodSync(lab, 0o755);

const workspace = path.join(lab, 'workspace'); fs.mkdirSync(workspace);

const outside = path.join(lab, 'outside-secret.txt'); fs.writeFileSync(outside, 'sensitive outside content\n');

const symlinkInside = path.join(workspace, 'innocent.txt'); fs.symlinkSync(outside, symlinkInside);

function validatePath(filePath, roots) { const absolutePath = path.resolve(filePath); for (const root of roots) { const rootPath = path.resolve(fileURLToPath(root.uri)); if ( absolutePath === rootPath || absolutePath.startsWith(rootPath + path.sep) ) { return true; } } throw new Error(Access denied: ${filePath}); }

const roots = [{uri: pathToFileURL(workspace).href, name: 'workspace'}]; validatePath(symlinkInside, roots);

fs.writeFileSync(symlinkInside, 'OVERWRITTEN BY MCP\n');

console.log(fs.readFileSync(outside, 'utf8')); // -> "OVERWRITTEN BY MCP" } finally { fs.rmSync(lab, {recursive: true, force: true}); }

Observed result:

text validatePath() accepts the in-root symlink path. The subsequent write follows the symlink and modifies the out-of-root target.

I can provide an end-to-end MCP client reproduction if needed. The lab PoC above demonstrates the root cause using the same validation logic as the server.

Impact

Who can exploit:

- A local process/user or trusted workflow that can create a symlink inside the workspace. - A remote page/prompt-injection attacker, if a suitable workspace-internal symlink already exists or can be created by another trusted workflow/tool.

Security impact:

- Integrity: tools that write to filePath can overwrite files outside the configured workspace root through an in-root symlink. - Confidentiality: uploadfile can read a file outside the workspace through an in-root symlink and attach it to a file input on the current page. - Stealth/auditability: the exfiltration path goes through normal page file-upload behavior, and chrome-devtools-mcp does not appear to log the canonical path that was uploaded.

Example sensitive files reachable if symlinked into the workspace:

- Cloud credentials such as ~/.aws/credentials, ~/.config/gcloud/..., or ~/.azure/.... - SSH private keys or .ssh files readable by the user. - Project secrets such as .env, .npmrc, .netrc, secrets.json, and API tokens. - Out-of-workspace source files or configuration files.

Severity:

- Suggested GitHub severity: Moderate. - CVSS v3.1 chain estimate: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N. - AC:H reflects that a workspace-internal symlink must exist at validation time.

Suggested fix:

Canonicalize paths before comparing against roots. For an existing file, use fs.realpath() on the path. For a new file, resolve the parent directory with fs.realpath() and re-join the basename.

ts async validatePath(filePath?: string): Promise<void> { if (filePath === undefined) return; const roots = this.roots(); if (roots === undefined) return;

const abs = path.resolve(filePath); let canonical; try { canonical = await fs.realpath(abs); } catch (err) { if (err.code === 'ENOENT') { const parent = await fs.realpath(path.dirname(abs)); canonical = path.join(parent, path.basename(abs)); } else { throw err; } }

for (const root of roots) { const canonicalRoot = await fs.realpath(fileURLToPath(root.uri)); if ( canonical === canonicalRoot || canonical.startsWith(canonicalRoot + path.sep) ) { return; } }

throw new Error( Access denied: ${filePath} (canonical: ${canonical}) is not within any workspace root., ); }

If the PATH environment variable contains paths which are executables (rather than just directories), passing certain strings to LookPath ("", ".", and ".."), can result in the binaries listed in the PATH being unexpectedly returned.

Validating certificate chains which use policies is unexpectedly inefficient when certificates in the chain contain a very large number of policy mappings, possibly causing denial of service. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello.

HTTP Proxy bypass using IPv6 Zone IDs in golang.org/x/net

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Kernel software installed and running inside a Guest/Host VM may post improper commands to the GPU Firmware to trigger a write of data outside the intended GPU memory.

A logic error in the address translation allowed a compromised Host (Kernel) to perform arbitrary writes to firmware memory.