CVE-2021-26957
📋 TL;DR
This vulnerability in the xcb Rust crate allows out-of-bounds memory reads when using the change_property() function, potentially exposing sensitive data or causing crashes. It affects Rust applications using the vulnerable xcb crate versions. Attackers could exploit this to read arbitrary memory from the application.
💻 Affected Systems
- xcb Rust crate
📦 What is this software?
Xcb by Xcb Project
⚠️ Risk & Real-World Impact
Worst Case
Arbitrary memory disclosure leading to sensitive information exposure, potential remote code execution through memory corruption, or application crashes.
Likely Case
Application crashes or denial of service, with potential information disclosure of adjacent memory contents.
If Mitigated
Limited impact if proper memory protections and sandboxing are in place, though information disclosure may still occur.
🎯 Exploit Status
Demonstrated proof-of-concept exists showing out-of-bounds read. Exploitation requires specific function calls but is straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: xcb crate version after 2021-02-04
Vendor Advisory: https://rustsec.org/advisories/RUSTSEC-2021-0019.html
Restart Required: Yes
Instructions:
1. Update Cargo.toml to use xcb crate version >0.9.0. 2. Run 'cargo update'. 3. Rebuild and redeploy application. 4. Restart affected services.
🔧 Temporary Workarounds
Avoid vulnerable function
allTemporarily avoid using xcb::xproto::change_property() with format=32 and T=u8 parameters
🧯 If You Can't Patch
- Implement strict input validation for xcb function parameters
- Deploy application in sandboxed/containerized environment with memory protection
🔍 How to Verify
Check if Vulnerable:
Check Cargo.lock for xcb crate version <=0.9.0 or check if application uses xcb::xproto::change_property()Check Version:
grep -A2 'name = "xcb"' Cargo.lockVerify Fix Applied:
Verify xcb crate version >0.9.0 in Cargo.lock and test application functionality📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory access violations
- Unexpected out-of-bounds read errors
Network Indicators:
- Unusual X11 protocol traffic patterns
- Excessive connection attempts to X server
SIEM Query:
process.name:rust_app AND (error:out_of_bounds OR error:segmentation_fault)