CVE-2021-29059
HIGHCVE-2021-29059 is a high-severity (CVSS 7.5) CWE-770 vulnerability in is-svg. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2021-29059 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
ReDOS in IS-SVG
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-29059 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
is-svgnpmDescription
A vulnerability was discovered in IS-SVG version 2.1.0 to 4.2.2 and below where a Regular Expression Denial of Service (ReDOS) occurs if the application is provided and checks a crafted invalid SVG string.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | is-svg | ≥ 2.1.0&&< 4.3.0 | 4.3.0 |
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 dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for is-svg. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update is-svg to 4.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29059 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.
How O3 protects you
O3 pinpoints whether CVE-2021-29059 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-29059. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Since OpenShift Service Mesh 1.1.x is in its maintenance phase, only Important and Criticals will be fixed at this time. In Red Hat OpenShift Container Platform (RHOCP) and OpenShift Service Mesh (OSSM), the affected components are behind OpenShift OAuth. This restricts access to the vulnerable is-svg library to…
Frequently Asked Questions
Is CVE-2021-29059 in your dependencies?
O3 detects CVE-2021-29059 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.