CVE-2021-47996

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-25. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

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

Nokogiri before 1.11.4 (CRuby implementation only, when the packaged/vendored libxml2 is used) bundles libxml2 2.9.10, which is affected by multiple vulnerabilities addressed in libxml2 2.9.12, including a memory leak in xmlSchemaValidateStream (CVE-2019-20388), a global buffer over-read in xmlEncodeEntitiesInternal (CVE-2020-24977), a heap-based buffer overflow (CVE-2021-3517), and an out-of-bounds read (CVE-2021-3518). Processing crafted XML documents may lead to denial of service, information disclosure, or memory corruption.

CVSS v3
7.5
EG Score
7.5(high)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
42%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Aug 25, 2026
Patch available. Sources: github.
github Patch Available

Update packaged libxml2 from 2.9.10 to 2.9.12 · Advisory · sparklemotion/nokogiri · GitHub

https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-7rrm-v45f-jp64

Vendor Advisories for CVE-2021-47996(1)

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

Affected Packages

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 27× in last 7d / 27× 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. 2026-08-30 06:26 UTCEG score recompute
  2. 2026-08-30 06:26 UTCGHSA enrichment
  3. 2026-08-30 01:19 UTCEPSS rescore
  4. 2026-08-29 18:41 UTCGHSA enrichment
  5. 2026-08-29 06:54 UTCEG score recompute
  6. 2026-08-29 06:54 UTCGHSA enrichment
  7. 2026-08-28 21:38 UTCEPSS rescore
  8. 2026-08-28 19:08 UTCGHSA enrichment
  9. 2026-08-28 16:44 UTCEG score recompute
  10. 2026-08-28 16:44 UTCGHSA enrichment
  11. 2026-08-28 15:52 UTCEG score recompute
  12. 2026-08-28 15:52 UTCGHSA enrichment
  13. 2026-08-28 05:57 UTCGHSA enrichment
  14. 2026-08-27 18:11 UTCEG score recompute
  15. 2026-08-27 18:11 UTCGHSA enrichment
  16. 2026-08-27 14:22 UTCEPSS rescore
  17. 2026-08-27 05:40 UTCGHSA enrichment
  18. 2026-08-26 17:53 UTCEG score recompute
  19. 2026-08-26 17:53 UTCGHSA enrichment
  20. 2026-08-26 14:43 UTCEPSS rescore
  21. 2026-08-26 06:07 UTCEG score recompute
  22. 2026-08-26 06:07 UTCGHSA enrichment
  23. 2026-08-25 18:18 UTCEG score recompute
  24. 2026-08-25 17:25 UTCEG score recompute
  25. 2026-08-25 16:24 UTCEG score recompute
Show 2 more
  1. 2026-08-25 15:30 UTCEG score recompute
  2. 2026-08-25 15:29 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47996?
CVE-2021-47996 is a high vulnerability published on August 25, 2026. Nokogiri before 1.11.4 (CRuby implementation only, when the packaged/vendored libxml2 is used) bundles libxml2 2.9.10, which is affected by multiple vulnerabilities addressed in libxml2 2.9.12, including a memory leak in xmlSchemaValidateStream (CVE-2019-20388), a global buffer over-read in…
When was CVE-2021-47996 disclosed?
CVE-2021-47996 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47996 actively exploited?
CVE-2021-47996 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 58.3% of all scored CVEs.
What is the CVSS score of CVE-2021-47996?
CVE-2021-47996 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2021-47996?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47996, 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.

Dependency Blast Radius

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