CVE-2021-3517

HIGHNVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 72% 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
8.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 8%CVSS: 8.6Exploit: NoneExposed: 0

A fix is available — apply it.

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application.

CVSS v3
8.6
EG Score
8.6(medium)
EPSS
94.3%
KEV
Not listed

Published

May 19, 2021

Last Modified

December 2, 2025

References (26)

Vendor Advisories for CVE-2021-3517(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibxml22022-04-20redhat
redhatjbcs-httpd24-openssl-pkcs11-0:0.4.10-26.jbcs.el72022-04-20redhat
redhatrhmtc/openshift-velero-plugin-rhel8:v1.4.6-42021-07-21redhat
redhatlibxml2-0:2.9.7-9.el8_4.22021-06-29redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
nokogiri1.0.0 ... 1.9.1 (128 versions)1.11.4—

Weakness Classification(2)

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

Additional Vendor Advisories

(4)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 47× 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.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-22 14:06 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-20 17:05 UTCEPSS rescore
  5. 2026-07-19 14:29 UTCEPSS rescore
  6. 2026-07-19 02:27 UTCEPSS rescore
  7. 2026-07-18 20:29 UTCOSV refresh
  8. 2026-07-18 10:02 UTCEPSS rescore
  9. 2026-07-18 10:02 UTCEPSS rescore
  10. 2026-07-16 17:00 UTCEPSS rescore
  11. 2026-07-16 17:00 UTCEPSS rescore
  12. 2026-07-15 16:55 UTCEPSS rescore
  13. 2026-07-15 16:55 UTCEPSS rescore
  14. 2026-07-15 01:58 UTCEPSS rescore
  15. 2026-07-13 22:27 UTCEPSS rescore
  16. 2026-07-13 22:27 UTCEPSS rescore
  17. 2026-07-12 05:44 UTCEPSS rescore
  18. 2026-07-11 08:25 UTCEPSS rescore
  19. 2026-07-11 08:25 UTCEPSS rescore
  20. 2026-07-09 19:07 UTCEPSS rescore
  21. 2026-07-08 15:12 UTCEPSS rescore
  22. 2026-07-07 13:43 UTCEPSS rescore
  23. 2026-07-06 16:25 UTCEPSS rescore
  24. 2026-07-06 16:25 UTCEPSS rescore
  25. 2026-07-06 02:21 UTCEPSS rescore
Show 75 more
  1. 2026-07-06 02:21 UTCEPSS rescore
  2. 2026-07-05 02:28 UTCEPSS rescore
  3. 2026-07-05 02:28 UTCEPSS rescore
  4. 2026-07-04 06:29 UTCEPSS rescore
  5. 2026-07-04 06:29 UTCEPSS rescore
  6. 2026-07-02 16:57 UTCEPSS rescore
  7. 2026-07-01 15:04 UTCEPSS rescore
  8. 2026-07-01 03:18 UTCOSV refresh
  9. 2026-06-30 23:20 UTCEPSS rescore
  10. 2026-06-30 23:20 UTCEPSS rescore
  11. 2026-06-29 14:04 UTCEPSS rescore
  12. 2026-06-28 14:05 UTCEPSS rescore
  13. 2026-06-28 04:54 UTCEPSS rescore
  14. 2026-06-28 04:54 UTCEPSS rescore
  15. 2026-06-27 03:06 UTCEPSS rescore
  16. 2026-06-27 03:06 UTCEPSS rescore
  17. 2026-06-25 13:48 UTCEPSS rescore
  18. 2026-06-25 13:48 UTCEPSS rescore
  19. 2026-06-24 14:03 UTCEPSS rescore
  20. 2026-06-24 14:03 UTCEPSS rescore
  21. 2026-06-23 21:31 UTCEPSS rescore
  22. 2026-06-23 21:31 UTCEPSS rescore
  23. 2026-06-22 14:24 UTCEPSS rescore
  24. 2026-06-21 14:55 UTCEPSS rescore
  25. 2026-06-21 01:58 UTCEPSS rescore
  26. 2026-06-21 01:58 UTCEPSS rescore
  27. 2026-06-18 17:51 UTCEPSS rescore
  28. 2026-06-18 17:51 UTCEPSS rescore
  29. 2026-06-17 17:51 UTCEPSS rescore
  30. 2026-06-17 17:51 UTCEPSS rescore
  31. 2026-06-17 17:51 UTCEPSS rescore
  32. 2026-06-16 17:51 UTCEPSS rescore
  33. 2026-06-16 17:51 UTCEPSS rescore
  34. 2026-06-15 17:46 UTCEPSS rescore
  35. 2026-06-14 23:15 UTCEPSS rescore
  36. 2026-06-14 23:15 UTCEPSS rescore
  37. 2026-06-13 22:58 UTCEPSS rescore
  38. 2026-06-13 22:58 UTCEPSS rescore
  39. 2026-06-13 05:13 UTCOSV refresh
  40. 2026-06-12 23:10 UTCEPSS rescore
  41. 2026-06-11 13:58 UTCEPSS rescore
  42. 2026-06-11 13:58 UTCEPSS rescore
  43. 2026-06-10 22:16 UTCEPSS rescore
  44. 2026-06-10 22:16 UTCEPSS rescore
  45. 2026-06-10 13:20 UTCEPSS rescore
  46. 2026-06-08 14:15 UTCEPSS rescore
  47. 2026-06-08 14:15 UTCEPSS rescore
  48. 2026-06-07 15:23 UTCEPSS rescore
  49. 2026-06-07 15:23 UTCEPSS rescore
  50. 2026-06-06 13:46 UTCEPSS rescore
  51. 2026-06-06 13:46 UTCEPSS rescore
  52. 2026-06-05 22:45 UTCEPSS rescore
  53. 2026-06-05 06:09 UTCEPSS rescore
  54. 2026-06-05 06:09 UTCEPSS rescore
  55. 2026-06-04 13:10 UTCEPSS rescore
  56. 2026-06-04 13:10 UTCEPSS rescore
  57. 2026-06-02 20:11 UTCEPSS rescore
  58. 2026-06-02 20:11 UTCEPSS rescore
  59. 2026-06-01 13:50 UTCEPSS rescore
  60. 2026-06-01 13:50 UTCEPSS rescore
  61. 2026-05-31 22:29 UTCEPSS rescore
  62. 2026-05-31 22:29 UTCEPSS rescore
  63. 2026-05-31 00:15 UTCEPSS rescore
  64. 2026-05-31 00:15 UTCEPSS rescore
  65. 2026-05-29 13:42 UTCEPSS rescore
  66. 2026-05-28 13:43 UTCEPSS rescore
  67. 2026-05-28 13:43 UTCEPSS rescore
  68. 2026-05-27 13:39 UTCEPSS rescore
  69. 2026-05-27 13:39 UTCEPSS rescore
  70. 2026-05-26 16:23 UTCEG score recompute
  71. 2026-05-26 16:23 UTCVendor advisory
  72. 2026-05-26 13:42 UTCEPSS rescore
  73. 2026-05-26 13:42 UTCEPSS rescore
  74. 2026-05-26 07:17 UTCEPSS rescore
  75. 2026-05-26 07:17 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-3517?
CVE-2021-3517 is a high vulnerability published on May 19, 2021. There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this…
When was CVE-2021-3517 disclosed?
CVE-2021-3517 was first published in the National Vulnerability Database on May 19, 2021, with the most recent update on December 2, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-3517 actively exploited?
CVE-2021-3517 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 94.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3517?
CVE-2021-3517 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2021-3517?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3517, 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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