CVE-2026-43820

HIGHPre-NVD 7.77.7
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 7.7 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.1% (1st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from CISA-ADP (Vulnrichment) CVSS v3.1
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS
Elevated

Also known asEUVD-2026-48287 (ENISA EUVD)Source: ENISA EUVD

7.7EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 7.7Exploit: No code on recordExposed services: Not assessed

The CVE record names the fixed release — apply it.

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
7.7HIGHmedium confidence
EG Risk
51
EG Risk 51/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity77% × 45%
Impact severity (EG Severity): CVSS 7.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The CVE record names the fixed release. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
1st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.7): severity, escalated by confirmed exploitation. This CVE's 7.7 is its impact severity (EG Severity), not escalated.

EG Severity
7.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.CISA-ADP (Vulnrichment) CVSS v3.1 · CVSS v3.1
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-07). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 23, 2026

Last Modified

October 24, 2026

Advisory Details (1)

Auto-updated Jul 24, 2026
Fix named in the CVE record. Sources: github.
GitHub advisoryMentions a patch (unverified)

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 6× in last 7d / 26× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 120 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 20 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  7. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  14. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  1. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  2. 2026-10-18 03:39 UTCEchelonGraph re-scored
  3. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  4. 2026-10-17 14:08 UTCEchelonGraph re-scored
  5. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  10. 2026-10-12 16:05 UTCEchelonGraph re-scored
  11. 2026-10-11 19:47 UTCEchelonGraph re-scored
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  14. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  29. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.1% · 1st percentile
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  56. 2026-09-04 05:06 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
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  58. 2026-08-28 21:41 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
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  61. 2026-08-23 00:19 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
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  63. 2026-08-19 17:04 UTCEPSS rescoreEPSS <0.1% · below the 1st percentile
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Frequently asked(5)

What is CVE-2026-43820?
CVE-2026-43820 is a high-severity vulnerability; its CVE record was 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 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…
When was the CVE record for CVE-2026-43820 published?
The CVE record for CVE-2026-43820 was published on July 23, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 24, 2026; the record at its source may have been updated since.
Is CVE-2026-43820 actively exploited?
CVE-2026-43820 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (1st percentile of EPSS-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?
The CVE record for CVE-2026-43820 names the fix: "This vulnerability is addressed in swift-nio-ssl version 2.37.2."

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