How severe is CVE-2021-29059?

CVE-2021-29059 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-29059?

CVE-2021-29059 affects the following packages: is-svg (npm). Ecosystems affected: npm.

How do I fix CVE-2021-29059?

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.

How do I detect CVE-2021-29059 in my npm dependencies?

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

How do I mitigate CVE-2021-29059 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-2021-29059 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-29059, including 1 in-the-wild exploitation 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-2021-29059?

CVE-2021-29059 has an EPSS (Exploit Prediction Scoring System) score of 2.6%, placing it in the 85th 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.

What type of vulnerability is CVE-2021-29059?

CVE-2021-29059 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-29059 published, and has it been updated?

CVE-2021-29059 was published on June 21, 2021 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.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2021-29059 — is-svg

HIGHFix: sindresorhus/is-svg@732fc72

CVE-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. A fix is available for is-svg — see the affected versions and patch details below.

ReDOS in IS-SVG

Also known asGHSA-r8j5-h5cx-65gg

Published

Jun 21, 2021

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

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

EPSS Exploitation Probability

via FIRST.org ↗

2.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs85th percentile — riskier than 85% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-29059 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.

243other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

is-svgnpm

1.7Mdownloads / week

Description

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`is-svg`	≥ 2.1.0&&< 4.3.0	4.3.0`npm install is-svg@4.3.0`

Affected Products

1 product · 1 configurations

Application

is-svgis-svg_project

≥ 2.1.0 && < 4.3.0

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.

A vulnerability was discovered in IS-SVG version 2.1.0 to 4.2.2 and belo…

github.comNVDJul 2021

Detection & mitigation playbook

Open-source dependency

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

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.

Red HatModerate

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…

Product	Fixed in	Advisory
Red Hat OpenShift Container Platform 4.8	`openshift4/ose-thanos-rhel8:v4.8.0-202106291913.p0.git.c358e96.assembly.stream`	RHSA-2021:2438
Red Hat OpenShift Container Platform 4.9	`openshift4/ose-prometheus:v4.9.0-202109302016.p0.git.3197fa7.assembly.stream`	RHSA-2021:3759

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-29059 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE Classification

CWE-770CWE-770

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

is-svg

3.5/10

Code-Review1/10

Maintained0/10

Branch-Protection0/10

Assessed Oct 5, 2026

Timeline

Disclosed

Jun 21, 2021

First exploit

Jul 6, 2021

Last updated

Jul 8, 2026

Identifiers

CVE-2021-29059

GHSA-r8j5-h5cx-65gg

References

Advisorygithub.com Advisorygithub.com Advisorynvd.nist.gov Fixgithub.com Webnpmjs.com Webgithub.com Packagegithub.com

Related vulnerabilities

Also affects is-svg

This CVE is high severity, in line with the other 1 CVE affecting is-svg.

CVE-2021-28092

Same weakness: CWE-770

This CVE is high severity; 3 of 7 other CVEs with CWE-770 are rated as high or higher (top: high).

CVE-2026-64847CVE-2026-77281CVE-2026-69147CVE-2026-81176CVE-2026-75516CVE-2026-82399CVE-2026-77403Browse all CWE-770

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 8, 2026

CVE-2021-29059 — is-svg

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2021-29059 in your dependencies?