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Not in CISA KEV
HIGH severity

CVE-2021-3810 — code-server

HIGHFix: cdr/code-server@ca617df

CVE-2021-3810 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in code-server. 1 public exploit reference exists, so weaponization risk is real. A fix is available for code-server — see the affected versions and patch details below.

Inefficient Regular Expression Complexity in code-server

Also known asGHSA-49x3-8228-3w3m
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 4, 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 CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk
0.00%0.59%1.17%1.76%0.2%1.3%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-3810 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

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

2other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
code-servernpm
6Kdownloads / week

Description

code-server is vulnerable to Inefficient Regular Expression Complexity

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmcode-serverall versions3.12.0npm install code-server@3.12.0

Affected Products

1 product · 1 configurations
Application
code-servercoder
< 3.12.0
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.

Detection & mitigation playbook

Open-source dependency
  1. Detect

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

  2. Fix

    Update code-server to 3.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3810 is resolved across your whole dependency graph.

  3. 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

code-server is vulnerable to Inefficient Regular Expression Complexity
O3 Security · Impact-Aware SCA

Is CVE-2021-3810 in your dependencies?

Find it across npm, including transitive dependencies.

CVE-2021-3810: code-server — Fixed in 3.12.0