How severe is CVE-2020-35909?

CVE-2020-35909 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-35909?

CVE-2020-35909 affects the following packages: multihash (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2020-35909?

Update multihash to 0.11.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35909 is resolved across your whole dependency graph.

How do I detect CVE-2020-35909 in my crates.io dependencies?

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

How do I mitigate CVE-2020-35909 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-2020-35909 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-35909 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-2020-35909?

CVE-2020-35909 has an EPSS (Exploit Prediction Scoring System) score of 1.4%, placing it in the 71th 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.

When was CVE-2020-35909 published, and has it been updated?

CVE-2020-35909 was published on December 31, 2020 and was last updated on July 8, 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

HIGH severity

CVE-2020-35909 — multihash

HIGHFix: multiformats/rust-multihash#72

CVE-2020-35909 is a high-severity (CVSS 7.5) vulnerability in multihash. A fix is available for multihash — see the affected versions and patch details below.

Unexpected panic in multihash

Also known asGHSA-h7qh-3h6f-w79pRUSTSEC-2020-0068

Published

Dec 31, 2020

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs71th percentile — riskier than 71% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2020-35909 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

🦀multihash

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

In versions prior 0.11.3 it's possible to make from_slice panic by feeding it certain malformed input. It's never documented that from_slice (and from_bytes which wraps it) can panic, and its' return type (Result<Self, DecodeError>) suggests otherwise. In practice, from_slice/from_bytes is frequently used in networking code and is being called with unsanitized data from untrusted sources. This can allow attackers to cause DoS by causing an unexpected panic in the network client's code..

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`multihash`	all versions	0.11.3`cargo update -p multihash --precise 0.11.3`

Affected Products

1 product · 1 configurations

Application

multihashprotocol

< 0.11.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for multihash, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update multihash to 0.11.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35909 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

O3 Security · Impact-Aware SCA

Is CVE-2020-35909 in your dependencies?

Find it across crates.io, including transitive dependencies.

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