CVE-2017-20202

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 70% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
9.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Web Developer for Chrome v0.4.9 contained malicious code that generated a domain via a DGA and fetched a remote script. The fetched script conditionally loaded follow-on modules that performed extensive ad substitution and malvertising, displayed fake “repair” alerts that redirected users to affiliate programs, and attempted to harvest credentials when users logged in. Injected components enumerate common banner sizes for substitution, replace third-party ad calls, and redirect victim traffic to affiliate landing pages. Potential impacts include user-level code execution in the browser context, large-scale ad fraud and traffic hijacking, credential theft, and exposure to additional payloads delivered by the actor. The compromise was reported on by the maintainer of Web Developer for Chrome on August 2, 2017 and remediated in v0.5.0.

CVSS v3
9.3
EG Score
9.3(medium)
EPSS
39.8%
KEV
Not listed

Published

October 8, 2025

Last Modified

April 15, 2026

Advisory Details (6)

Auto-updated Jul 17, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

Threat actor goes on a Chrome extension hijacking spree | Proofpoint US

https://www.proofpoint.com/us/threat-insight/post/threat-actor-goes-chrome-extension-hijacking-spree
generic🔴 Active Exploitation

Web Developer for Chrome v0.4.9 Malicious Backdoor Supply Chain Compromise | Advisories | VulnCheck

https://www.vulncheck.com/advisories/web-developer-for-chrome-malicious-backdoor-supply-chain-compromise
generic

Web Developer for Chrome Compromised on Blog on chrispederick.com

https://web.archive.org/web/20170803163618/https://chrispederick.com/blog/web-developer-for-chrome-compromised/
generic

Our Copyfish extension was stolen and adware-infested **[Solved]**

https://ui.vision/blog/chrome-extension-adware/
generic

Web developer 0.4.9 tools hacked and installing adware Decode · GitHub

https://gist.github.com/piedpiperRichard/076516da60f45842f1a6e6ae35a9a240/
generic

Web Developer - Chrome Web Store

https://chromewebstore.google.com/detail/web-developer/bfbameneiokkgbdmiekhjnmfkcnldhhm?pli=1

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:04 UTCEPSS rescore
  2. 2026-07-22 14:04 UTCEPSS rescore
  3. 2026-07-21 15:21 UTCEPSS rescore
  4. 2026-07-21 15:21 UTCEPSS rescore
  5. 2026-07-20 17:04 UTCEPSS rescore
  6. 2026-07-19 14:28 UTCEPSS rescore
  7. 2026-07-19 14:28 UTCEPSS rescore
  8. 2026-07-19 02:26 UTCEPSS rescore
  9. 2026-07-19 02:26 UTCEPSS rescore
  10. 2026-07-18 10:00 UTCEPSS rescore
  11. 2026-07-16 16:59 UTCEPSS rescore
  12. 2026-07-16 16:59 UTCEPSS rescore
  13. 2026-07-15 16:54 UTCEPSS rescore
  14. 2026-07-15 01:56 UTCEPSS rescore
  15. 2026-07-15 01:56 UTCEPSS rescore
  16. 2026-07-13 22:26 UTCEPSS rescore
  17. 2026-07-12 05:43 UTCEPSS rescore
  18. 2026-07-11 08:24 UTCEPSS rescore
  19. 2026-07-09 19:06 UTCEPSS rescore
  20. 2026-07-08 15:10 UTCEPSS rescore
  21. 2026-07-07 13:42 UTCEPSS rescore
  22. 2026-07-06 16:24 UTCEPSS rescore
  23. 2026-07-06 16:24 UTCEPSS rescore
  24. 2026-07-06 02:20 UTCEPSS rescore
  25. 2026-07-06 02:20 UTCEPSS rescore
Show 72 more
  1. 2026-07-05 02:27 UTCEPSS rescore
  2. 2026-07-04 06:28 UTCEPSS rescore
  3. 2026-07-02 16:54 UTCEPSS rescore
  4. 2026-07-01 15:02 UTCEPSS rescore
  5. 2026-06-30 23:19 UTCEPSS rescore
  6. 2026-06-30 23:19 UTCEPSS rescore
  7. 2026-06-29 14:03 UTCEPSS rescore
  8. 2026-06-28 14:04 UTCEPSS rescore
  9. 2026-06-28 04:53 UTCEPSS rescore
  10. 2026-06-27 03:06 UTCEPSS rescore
  11. 2026-06-27 03:05 UTCEPSS rescore
  12. 2026-06-25 13:47 UTCEPSS rescore
  13. 2026-06-24 14:02 UTCEPSS rescore
  14. 2026-06-24 14:02 UTCEPSS rescore
  15. 2026-06-23 21:30 UTCEPSS rescore
  16. 2026-06-22 14:23 UTCEPSS rescore
  17. 2026-06-22 14:23 UTCEPSS rescore
  18. 2026-06-21 14:54 UTCEPSS rescore
  19. 2026-06-21 14:54 UTCEPSS rescore
  20. 2026-06-21 01:57 UTCEPSS rescore
  21. 2026-06-21 01:57 UTCEPSS rescore
  22. 2026-06-19 19:23 UTCEPSS rescore
  23. 2026-06-19 19:23 UTCEPSS rescore
  24. 2026-06-18 17:50 UTCEPSS rescore
  25. 2026-06-17 17:50 UTCEPSS rescore
  26. 2026-06-16 17:50 UTCEPSS rescore
  27. 2026-06-16 17:50 UTCEPSS rescore
  28. 2026-06-15 17:45 UTCEPSS rescore
  29. 2026-06-14 23:14 UTCEPSS rescore
  30. 2026-06-13 22:57 UTCEPSS rescore
  31. 2026-06-12 23:09 UTCEPSS rescore
  32. 2026-06-10 22:15 UTCEPSS rescore
  33. 2026-06-10 13:19 UTCEPSS rescore
  34. 2026-06-08 15:25 UTCEG score recompute▲ 9.30
  35. 2026-06-08 15:25 UTCGHSA enrichment
  36. 2026-06-08 14:14 UTCEPSS rescore
  37. 2026-06-08 14:14 UTCEPSS rescore
  38. 2026-06-07 15:22 UTCEPSS rescore
  39. 2026-06-07 15:22 UTCEPSS rescore
  40. 2026-06-06 13:45 UTCEPSS rescore
  41. 2026-06-06 13:45 UTCEPSS rescore
  42. 2026-06-05 22:44 UTCEPSS rescore
  43. 2026-06-05 06:08 UTCEPSS rescore
  44. 2026-06-05 06:08 UTCEPSS rescore
  45. 2026-06-04 13:10 UTCEPSS rescore
  46. 2026-06-02 20:11 UTCEPSS rescore
  47. 2026-06-02 20:11 UTCEPSS rescore
  48. 2026-06-01 13:49 UTCEPSS rescore
  49. 2026-05-31 22:28 UTCEPSS rescore
  50. 2026-05-31 22:28 UTCEPSS rescore
  51. 2026-05-31 00:14 UTCEPSS rescore
  52. 2026-05-31 00:14 UTCEPSS rescore
  53. 2026-05-29 13:41 UTCEPSS rescore
  54. 2026-05-28 13:42 UTCEPSS rescore
  55. 2026-05-28 13:42 UTCEPSS rescore
  56. 2026-05-27 13:38 UTCEPSS rescore
  57. 2026-05-27 13:38 UTCEPSS rescore
  58. 2026-05-26 13:42 UTCEPSS rescore
  59. 2026-05-26 13:42 UTCEPSS rescore
  60. 2026-05-26 07:17 UTCEPSS rescore
  61. 2026-05-26 07:17 UTCEPSS rescore
  62. 2026-05-22 21:15 UTCEPSS rescore
  63. 2026-05-22 21:15 UTCEPSS rescore
  64. 2026-05-22 21:15 UTCEPSS rescore
  65. 2026-05-22 21:15 UTCEPSS rescore
  66. 2026-05-22 21:15 UTCEPSS rescore
  67. 2026-05-21 22:40 UTCEPSS rescore
  68. 2026-05-21 06:46 UTCEG score recompute
  69. 2026-05-21 06:45 UTCGHSA enrichment
  70. 2026-05-20 11:21 UTCEPSS rescore
  71. 2026-05-20 11:21 UTCEPSS rescore
  72. 2026-05-18 21:30 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2017-20202?
CVE-2017-20202 is a critical vulnerability published on October 8, 2025. Web Developer for Chrome v0.4.9 contained malicious code that generated a domain via a DGA and fetched a remote script. The fetched script conditionally loaded follow-on modules that performed extensive ad substitution and malvertising, displayed fake “repair” alerts that redirected users to…
When was CVE-2017-20202 disclosed?
CVE-2017-20202 was first published in the National Vulnerability Database on October 8, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2017-20202 actively exploited?
CVE-2017-20202 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 39.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2017-20202?
CVE-2017-20202 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2017-20202?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2017-20202, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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