CVE-2026-43820

HIGHPre-NVD 7.77.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.7 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 100% 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: cisa-adp, epss
Elevated
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.7Exploit: Elevated riskExposed: 0

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

NIOSSLCertificate._subjectAlternativeNames provides access to the raw bytes for a cert's SANs. NIOSSL provides access to a buffer assumed to be backed by an ASN1_STRING, but not all SANs are backed by ASN1_STRING, so accessing the buffer for such a type can lead to out-of-bounds memory access. This vulnerability is addressed in swift-nio-ssl version 2.37.2.

CVSS v3
7.7
EG Score
7.7(medium)
EG Risk
51(Track)
EG Risk 51/100SSVC: 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
Severity77% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
0%
KEV
Not listed

Published

July 23, 2026

Last Modified

July 24, 2026

Advisory Details (1)

Auto-updated Jul 24, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Accessing bytes of non-string SAN can lead to out-of-bounds memory read · Advisory · apple/swift-nio-ssl · GitHub

https://github.com/apple/swift-nio-ssl/security/advisories/GHSA-xfxg-9975-pc2j

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 3× in last 7d / 21× 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 00:33 UTCEG score recompute
  2. 2026-08-28 21:41 UTCEPSS rescore
  3. 2026-08-24 15:49 UTCEG score recompute
  4. 2026-08-23 05:06 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-19 20:33 UTCEG score recompute
  7. 2026-08-19 17:04 UTCEPSS rescore
  8. 2026-08-16 07:04 UTCEG score recompute
  9. 2026-08-16 02:14 UTCEPSS rescore
  10. 2026-08-14 09:04 UTCEG score recompute
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-13 21:34 UTCEG score recompute
  13. 2026-08-06 17:06 UTCEG score recompute
  14. 2026-08-06 13:46 UTCEPSS rescore
  15. 2026-08-06 05:36 UTCEG score recompute
  16. 2026-08-05 19:17 UTCEPSS rescore
  17. 2026-08-04 19:05 UTCEG score recompute
  18. 2026-08-04 15:10 UTCEPSS rescore
  19. 2026-08-04 10:38 UTCEPSS rescore
  20. 2026-08-01 10:10 UTCEG score recompute
  21. 2026-08-01 04:16 UTCEPSS rescore
  22. 2026-07-30 23:38 UTCEG score recompute
  23. 2026-07-30 16:28 UTCEPSS rescore
  24. 2026-07-30 12:09 UTCEG score recompute
  25. 2026-07-30 01:30 UTCEPSS rescore
Show 14 more
  1. 2026-07-27 15:05 UTCEG score recompute
  2. 2026-07-27 14:13 UTCEPSS rescore
  3. 2026-07-27 02:07 UTCEG score recompute
  4. 2026-07-26 14:54 UTCEPSS rescore
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-26 14:37 UTCEG score recompute
  7. 2026-07-26 03:07 UTCEG score recompute
  8. 2026-07-25 14:18 UTCEPSS rescore
  9. 2026-07-24 20:42 UTCEG score recompute▲ 7.70
  10. 2026-07-24 20:41 UTCMITRE cvelistV5CVSS v3 → 7.7 · severity → HIGH
  11. 2026-07-24 14:17 UTCEPSS rescore
  12. 2026-07-23 16:11 UTCNVD update
  13. 2026-07-23 14:57 UTCEG score recompute
  14. 2026-07-23 14:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-43820?
CVE-2026-43820 is a high vulnerability published on July 23, 2026. NIOSSLCertificate.subjectAlternativeNames provides access to the raw bytes for a cert's SANs. NIOSSL provides access to a buffer assumed to be backed by an ASN1STRING, but not all SANs are backed by ASN1_STRING, so accessing the buffer for such a type can lead to out-of-bounds memory access. This…
When was CVE-2026-43820 disclosed?
CVE-2026-43820 was first published in the National Vulnerability Database on July 23, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-43820 actively exploited?
CVE-2026-43820 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 99.9% of all scored CVEs.
What is the CVSS score of CVE-2026-43820?
CVE-2026-43820 has a CVSS v3.1 base score of 7.7 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-43820?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-43820, 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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