How severe is CVE-2020-35918?

CVE-2020-35918 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-35918?

CVE-2020-35918 affects the following packages: branca (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2020-35918?

Update branca to 0.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35918 is resolved across your whole dependency graph.

How do I detect CVE-2020-35918 in my crates.io dependencies?

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

How do I mitigate CVE-2020-35918 if there is no patch (or I can't update yet)?

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.

Is CVE-2020-35918 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2020-35918, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-35918?

CVE-2020-35918 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 39th 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-2020-35918 published, and has it been updated?

CVE-2020-35918 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

MEDIUM severity

CVE-2020-35918 — branca

MEDIUMFix: return/branca@7da3274

CVE-2020-35918 is a medium-severity (CVSS 5.5) vulnerability in branca. 2 public exploit references exist, so weaponization risk is real. A fix is available for branca — see the affected versions and patch details below.

Unexpected panic when decoding tokens in branca

Also known asGHSA-c9rv-3jmq-527wRUSTSEC-2020-0075

Published

Dec 31, 2020

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

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

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs39th percentile — riskier than 39% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2020-35918 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

🦀branca

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

Prior to 0.10.0 it was possible to have both decoding functions panic unexpectedly, by supplying tokens with an incorrect base62 encoding. The documentation stated that an error should have been reported instead.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`branca`	all versions	0.10.0`cargo update -p branca --precise 0.10.0`

Affected Products

1 product · 1 configurations

Application

brancahakobaito

< 0.10.0

range

Exploits & PoCs

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 branca crate before 0.10.0 for Rust. Deco…

rustsec.orgNVDJan 2021

An issue was discovered in the branca crate before 0.10.0 for Rust. Deco…

github.comNVDSep 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for branca, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update branca to 0.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35918 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.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2020-35918 in your dependencies?

Find it across crates.io, including transitive dependencies.

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