CVE-2021-29511
MEDIUMCVE-2021-29511 is a medium-severity (CVSS 6.5) CWE-770 vulnerability in evm. O3 Security confirms whether CVE-2021-29511 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Memory over-allocation in evm crate
Blast Radius
evm🦀evm-core🦀evm🦀evm🦀evm🦀evm🦀evm🦀evm-core+4 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
evm is a pure Rust implementation of Ethereum Virtual Machine. Prior to the patch, when executing specific EVM opcodes related to memory operations that use evm_core::Memory::copy_large, the evm crate can over-allocate memory when it is not needed, making it possible for an attacker to perform denial-of-service attack. The flaw was corrected in commit 19ade85. Users should upgrade to ==0.21.1, ==0.23.1, ==0.24.1, ==0.25.1, >=0.26.1. There are no workarounds. Please upgrade your evm crate version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | evm | all versions | 0.21.1 |
| 🦀crates.io | evm-core | all versions | 0.21.1 |
| 🦀crates.io | evm | ≥ 0.22.0&&< 0.22.1 | 0.22.1 |
| 🦀crates.io | evm | ≥ 0.23.0&&< 0.23.1 | 0.23.1 |
| 🦀crates.io | evm | ≥ 0.24.0&&< 0.24.1 | 0.24.1 |
| 🦀crates.io | evm | ≥ 0.25.0&&< 0.25.1 | 0.25.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for evm. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update evm to 0.21.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29511 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-29511 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-29511. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-29511 in your dependencies?
O3 detects CVE-2021-29511 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.