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🦀 crates.io
Not in CISA KEV
HIGH severity

CVE-2020-35861 — bumpalo

HIGH

CVE-2020-35861 is a high-severity (CVSS 7.5) Out-of-bounds Read vulnerability in bumpalo. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for bumpalo — see the affected versions and patch details below.

Out of bounds read in bumpalo

Also known asGHSA-vqx7-pw4r-29rrRUSTSEC-2020-0006
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk
0.00%0.67%1.34%2.01%0.3%1.5%Apr 26Aug 26Oct 26

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

1 pkg affected
🦀bumpalo

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 bumpalo crate before 3.2.1 for Rust. The realloc feature allows the reading of unknown memory. Attackers can potentially read cryptographic keys.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iobumpalo≥ 3.0.0&&< 3.2.13.2.1cargo update -p bumpalo --precise 3.2.1

Affected Products

1 product · 1 configurations
Application
bumpalobumpalo_project
≥ 3.0.0 && < 3.2.1
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

An issue was discovered in the bumpalo crate before 3.2.1 for Rust. The …

rustsec.orgNVDJan 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update bumpalo to 3.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35861 is resolved across your whole dependency graph.

  3. Workarounds

    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 bumpalo crate before 3.2.1 for Rust. The realloc feature allows the reading of unknown memory. Attackers can potentially read cryptographic keys.
O3 Security · Impact-Aware SCA

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CVE-2020-35861: bumpalo — Fixed in 3.2.1