CVE-2020-36323
📋 TL;DR
This vulnerability in Rust's standard library before version 1.52.0 allows uninitialized memory exposure or program crashes when joining strings. It occurs due to an optimization that doesn't properly handle borrowed strings that change after length validation. Any Rust application using string joining operations is potentially affected.
💻 Affected Systems
- Rust programming language standard library
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
Rust by Rust Lang
⚠️ Risk & Real-World Impact
Worst Case
Memory corruption leading to arbitrary code execution, information disclosure of sensitive memory contents, or denial of service through program crashes.
Likely Case
Program crashes or exposure of uninitialized memory contents, potentially leaking sensitive information from the application's memory space.
If Mitigated
No impact if patched or if affected code paths aren't used in the application.
🎯 Exploit Status
Exploitation requires crafting specific string manipulation patterns. Proof-of-concept code exists in the GitHub issue tracker.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Rust 1.52.0 and later
Vendor Advisory: https://github.com/rust-lang/rust/issues/80335
Restart Required: Yes
Instructions:
1. Update Rust toolchain to version 1.52.0 or later using rustup update. 2. Recompile all Rust applications with the updated toolchain. 3. Redeploy updated applications.
🔧 Temporary Workarounds
Avoid mutable string borrowing in join operations
allModify code to avoid using mutable borrowed strings that could change during string joining operations.
🧯 If You Can't Patch
- Review and audit all string joining operations in codebase for unsafe patterns
- Implement input validation and sanitization for all string processing operations
🔍 How to Verify
Check if Vulnerable:
Check Rust version with 'rustc --version'. If version is earlier than 1.52.0, the system is vulnerable.Check Version:
rustc --versionVerify Fix Applied:
Verify Rust version is 1.52.0 or later with 'rustc --version' and recompile applications.📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults
- Unexpected memory access errors in logs
Network Indicators:
- Unusual patterns of string manipulation requests
SIEM Query:
Application logs containing 'segmentation fault', 'SIGSEGV', or memory access errors from Rust applications🔗 References
- https://github.com/rust-lang/rust/issues/80335
- https://github.com/rust-lang/rust/pull/81728
- https://github.com/rust-lang/rust/pull/81728#issuecomment-821549174
- https://github.com/rust-lang/rust/pull/81728#issuecomment-824904190
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CZ337CM4GFJLRDFVQCGC7J25V65JXOG5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFUO3URYCO73D2Q4WYJBWAMJWGGVXQO4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VZG65GUW6Z2CYOQHF7T3TB5CZKIX6ZJE/
- https://github.com/rust-lang/rust/issues/80335
- https://github.com/rust-lang/rust/pull/81728
- https://github.com/rust-lang/rust/pull/81728#issuecomment-821549174
- https://github.com/rust-lang/rust/pull/81728#issuecomment-824904190
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CZ337CM4GFJLRDFVQCGC7J25V65JXOG5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFUO3URYCO73D2Q4WYJBWAMJWGGVXQO4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VZG65GUW6Z2CYOQHF7T3TB5CZKIX6ZJE/
