How severe is CVE-2021-29511?

CVE-2021-29511 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-29511?

CVE-2021-29511 affects the following packages: evm (crates.io), evm-core (crates.io), evm (crates.io), evm (crates.io), evm (crates.io), evm (crates.io), evm (crates.io), evm-core (crates.io), and 4 more. Ecosystems affected: crates.io.

How do I fix CVE-2021-29511?

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.

How do I detect CVE-2021-29511 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for evm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-29511 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2021-29511 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-29511 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-29511?

CVE-2021-29511 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-29511?

CVE-2021-29511 is classified as CWE-770 (CWE-770), Out-of-bounds Write (CWE-787). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-29511 published, and has it been updated?

CVE-2021-29511 was published on May 12, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io

Not in CISA KEV

MEDIUM severity

CVE-2021-29511 — evm

MEDIUMFix: rust-blockchain/evm@19ade85

CVE-2021-29511 is a medium-severity (CVSS 6.5) CWE-770 vulnerability in evm. A fix is available for evm — see the affected versions and patch details below.

Memory over-allocation in evm crate

Also known asGHSA-4jwq-572w-4388

Published

May 12, 2021

Updated

Oct 24, 2026

Affected

12 pkgs

Patched

12 / 12

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

12 pkgs affected

🦀evm🦀evm-core🦀evm🦀evm🦀evm🦀evm🦀evm🦀evm-core+4 more

Real-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

Impact

Prior to the patch, when executing specific EVM opcodes related to memory operations that use evm_core::Memory::copy_large, the crate can over-allocate memory when it is not needed, making it possible for an attacker to perform denial-of-service attack.

Patches

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.

Workarounds

None. Please upgrade your evm crate version

References

Fix commit: https://github.com/rust-blockchain/evm/commit/19ade858c430ab13eb562764a870ac9f8506f8dd

For more information

If you have any questions or comments about this advisory:

Open an issue in evm repo
Email Wei

Affected Packages

12 total 12 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`evm`	all versions	0.21.1`cargo update -p evm --precise 0.21.1`
🦀crates.io	`evm-core`	all versions	0.21.1`cargo update -p evm-core --precise 0.21.1`
🦀crates.io	`evm`	≥ 0.22.0&&< 0.22.1	0.22.1`cargo update -p evm --precise 0.22.1`
🦀crates.io	`evm`	≥ 0.23.0&&< 0.23.1	0.23.1`cargo update -p evm --precise 0.23.1`
🦀crates.io	`evm`	≥ 0.24.0&&< 0.24.1	0.24.1`cargo update -p evm --precise 0.24.1`
🦀crates.io	`evm`	≥ 0.25.0&&< 0.25.1	0.25.1`cargo update -p evm --precise 0.25.1`

Affected Products

1 product · 6 configurations

Application

evmevm_project

≤ 0.21.0

5 versions

0.22.00.23.00.24.00.25.00.26.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for evm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact Prior to the patch, when executing specific EVM opcodes related to memory operations that use `evm_core::Memory::copy_large`, the crate can over-allocate memory when it is not needed, making it possible for an attacker to perform denial-of-service attack. ### Patches 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`. ### Workarounds None. Please upgrade your `evm` crate version ### References Fix commit: https://github.com/rust-blockchain/evm/commit/19ade858c430ab13eb562764a870ac9f8506f8dd ### For more informat