CVE-2016-9909

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 35% 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
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 6.1Exploit: NoneExposed: 0

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

The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of the < (less than) character in attribute values.

CVSS v3
6.1
EG Score
6.1(medium)
EPSS
79.9%
KEV
Not listed

Published

February 22, 2017

Last Modified

May 13, 2026

References (14)

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
html5lib0.10 ... 0.99999999 (14 versions)0.999999999—

Data Freshness Timeline

(refreshed 11× in last 7d / 41× 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. 2026-07-12 05:43 UTCEPSS rescore
  2. 2026-07-12 05:43 UTCEPSS rescore
  3. 2026-07-12 02:52 UTCOSV refresh
  4. 2026-07-11 08:24 UTCEPSS rescore
  5. 2026-07-09 19:06 UTCEPSS rescore
  6. 2026-07-08 15:10 UTCEPSS rescore
  7. 2026-07-07 13:42 UTCEPSS rescore
  8. 2026-07-06 16:24 UTCEPSS rescore
  9. 2026-07-06 16:24 UTCEPSS rescore
  10. 2026-07-06 02:20 UTCEPSS rescore
  11. 2026-07-06 02:20 UTCEPSS rescore
  12. 2026-07-05 02:27 UTCEPSS rescore
  13. 2026-07-04 06:28 UTCEPSS rescore
  14. 2026-07-01 15:02 UTCEPSS rescore
  15. 2026-06-30 23:19 UTCEPSS rescore
  16. 2026-06-30 23:19 UTCEPSS rescore
  17. 2026-06-29 14:03 UTCEPSS rescore
  18. 2026-06-28 14:04 UTCEPSS rescore
  19. 2026-06-28 04:53 UTCEPSS rescore
  20. 2026-06-27 03:05 UTCEPSS rescore
  21. 2026-06-25 13:47 UTCEPSS rescore
  22. 2026-06-24 14:02 UTCEPSS rescore
  23. 2026-06-23 21:30 UTCEPSS rescore
  24. 2026-06-23 09:30 UTCOSV refresh
  25. 2026-06-21 14:54 UTCEPSS rescore
Show 52 more
  1. 2026-06-21 14:54 UTCEPSS rescore
  2. 2026-06-21 01:57 UTCEPSS rescore
  3. 2026-06-21 01:57 UTCEPSS rescore
  4. 2026-06-19 19:23 UTCEPSS rescore
  5. 2026-06-19 19:23 UTCEPSS rescore
  6. 2026-06-18 17:50 UTCEPSS rescore
  7. 2026-06-18 17:50 UTCEPSS rescore
  8. 2026-06-17 17:50 UTCEPSS rescore
  9. 2026-06-17 17:50 UTCEPSS rescore
  10. 2026-06-16 17:50 UTCEPSS rescore
  11. 2026-06-15 17:45 UTCEPSS rescore
  12. 2026-06-14 23:14 UTCEPSS rescore
  13. 2026-06-14 23:14 UTCEPSS rescore
  14. 2026-06-13 22:57 UTCEPSS rescore
  15. 2026-06-13 22:57 UTCEPSS rescore
  16. 2026-06-12 23:09 UTCEPSS rescore
  17. 2026-06-11 13:57 UTCEPSS rescore
  18. 2026-06-08 14:14 UTCEPSS rescore
  19. 2026-06-07 15:22 UTCEPSS rescore
  20. 2026-06-07 15:22 UTCEPSS rescore
  21. 2026-06-06 13:45 UTCEPSS rescore
  22. 2026-06-06 13:45 UTCEPSS rescore
  23. 2026-06-06 09:03 UTCOSV refresh
  24. 2026-06-05 22:44 UTCEPSS rescore
  25. 2026-06-05 06:08 UTCEPSS rescore
  26. 2026-06-05 06:08 UTCEPSS rescore
  27. 2026-06-04 13:10 UTCEPSS rescore
  28. 2026-06-04 13:10 UTCEPSS rescore
  29. 2026-06-02 20:10 UTCEPSS rescore
  30. 2026-05-31 22:28 UTCEPSS rescore
  31. 2026-05-31 22:28 UTCEPSS rescore
  32. 2026-05-31 00:14 UTCEPSS rescore
  33. 2026-05-29 13:41 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-28 13:42 UTCEPSS rescore
  36. 2026-05-27 13:38 UTCEPSS rescore
  37. 2026-05-27 13:38 UTCEPSS rescore
  38. 2026-05-26 13:42 UTCEPSS rescore
  39. 2026-05-26 13:42 UTCEPSS rescore
  40. 2026-05-26 07:17 UTCEPSS rescore
  41. 2026-05-24 16:44 UTCEPSS rescore
  42. 2026-05-23 00:10 UTCEG score recompute
  43. 2026-05-22 21:15 UTCEPSS rescore
  44. 2026-05-22 15:56 UTCEG score recompute
  45. 2026-05-20 22:37 UTCEPSS rescore
  46. 2026-05-20 22:37 UTCEPSS rescore
  47. 2026-05-20 22:37 UTCEPSS rescore
  48. 2026-05-20 11:21 UTCEPSS rescore
  49. 2026-05-20 11:21 UTCEPSS rescore
  50. 2026-05-18 21:30 UTCEPSS rescore
  51. 2026-05-18 21:30 UTCEPSS rescore
  52. 2026-05-18 21:30 UTCEPSS rescore

Frequently asked(5)

What is CVE-2016-9909?
CVE-2016-9909 is a medium vulnerability published on February 22, 2017. The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of the < (less than) character in attribute values.
When was CVE-2016-9909 disclosed?
CVE-2016-9909 was first published in the National Vulnerability Database on February 22, 2017, with the most recent update on May 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-9909 actively exploited?
CVE-2016-9909 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 79.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-9909?
CVE-2016-9909 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2016-9909?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-9909, 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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