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CRITICAL severity

CVE-2020-35876 — rio

CRITICALFix: spacejam/rio#31

CVE-2020-35876 is a critical-severity (CVSS 9.8) Use After Free vulnerability in rio. No vendor fix is recorded yet; mitigation options are listed below.

Use after free in rio

Also known asRUSTSEC-2020-0021
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs75th percentile — riskier than 75% of all scored CVEsHighest risk
0.01%0.69%1.38%2.06%0.5%1.6%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-35876 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀rio

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

An issue was discovered in the rio crate through 2020-05-11 for Rust. A struct can be leaked, allowing attackers to obtain sensitive information, cause a use-after-free, or cause a data race.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🦀crates.iorioall versionsNo fix

Affected Products

1 product · 1 configurations
Application
riorio_project
≤ 0.9.3
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Remediation status

    No patched version of rio has shipped for CVE-2020-35876 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

An issue was discovered in the rio crate through 2020-05-11 for Rust. A struct can be leaked, allowing attackers to obtain sensitive information, cause a use-after-free, or cause a data race.
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CVE-2020-35876: rio: Use after free