CVE-2023-26133 is a high-severity (CVSS 8.2) CWE-1321 vulnerability in progressbar.js. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for progressbar.js — see the affected versions and patch details below.
progressbar.js vulnerable to Prototype Pollution
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-26133.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
progressbar.jsnpmDescription
All versions of the package progressbar.js prior to 1.1.1 are vulnerable to Prototype Pollution via the function extend() in the file utils.js.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | progressbar.js | all versions | 1.1.1npm install progressbar.js@1.1.1 |
Affected Products
progressbar.jsprogressbar.js_projectResearch 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 progressbar.js, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update progressbar.js to 1.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-26133 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
Is CVE-2023-26133 in your dependencies?
Find it across npm, including transitive dependencies.