MsQuic is a cross-platform C implementation of the IETF QUIC protocol exposed to C, C++, C#, and Rust. Prior to 2.4.20, 2.5.11, and 2.6.1, MsQuic clients using the OpenSSL or QuicTLS TLS backend do not properly verify that a server certificate matches the intended target server hostname. An on-path attacker can therefore present a certificate that does not match the intended target hostname and spoof the server in a man-in-the-middle attack. The Schannel backend is not affected. This issue is fixed in versions 2.4.20, 2.5.11, and 2.6.1.
CVE-2026-105794
“—” beside the score: it is equal to the CVSS score beside it.
This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.0% (62nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-93422 (ENISA EUVD) · GHSA-w5f4-fx9m-m4q7 (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.1
- EG Score
- 9.1CRITICALmedium confidence
- EG Risk
- 41EG Risk 41/100
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)Severity91% × 45%Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation1.0% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (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: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 1.0%
- EPSS %ILE
- 62nd
- 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 (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 1.0% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-02). 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 every mission impact level.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 every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (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
October 6, 2026
Last Modified
October 6, 2026
Advisory Details (10)
Auto-updated Oct 6, 2026v2.4.20
Patch available: microsoft/msquic v2.4.20
https://github.com/microsoft/msquic/releases/tag/v2.4.20commit a01333cf7c26 (microsoft/msquic)
Patch available: microsoft/msquic v2.6.1 (contains commit a01333cf7c26)
https://github.com/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83commit 90fd45498bf9 (microsoft/msquic)
Patch available: microsoft/msquic v2.4.20 (contains commit 90fd45498bf9)
https://github.com/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81commit 508e811370df (microsoft/msquic)
Fix landed in microsoft/msquic commit 508e811370df — awaiting tagged release
https://github.com/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91commit 0591586443cc (microsoft/msquic)
Patch available: microsoft/msquic v2.5.11 (contains commit 0591586443cc)
https://github.com/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412[CP] Fix hostname validation with OpenSSL/QuicTLS (#6274)
Patch available: microsoft/msquic v2.4.20 (PR #6277 merged 2026-08-28)
https://github.com/microsoft/msquic/pull/6277[CP] Fix hostname validation with OpenSSL/QuicTLS (#6274)
Patch available: microsoft/msquic v2.5.11 (PR #6276 merged 2026-08-28)
https://github.com/microsoft/msquic/pull/6276[CP] Fix hostname validation with OpenSSL/QuicTLS (#6274)
Patch available: microsoft/msquic v2.6.1 (PR #6275 merged 2026-08-28)
https://github.com/microsoft/msquic/pull/6275Fix hostname validation with OpenSSL/QuicTLS
Fix merged in microsoft/msquic PR #6274 on 2026-08-28 — awaiting tagged release
https://github.com/microsoft/msquic/pull/6274Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL · Advisory · microsoft/msquic · GitHub
https://github.com/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7Vendor Advisories for CVE-2026-105794(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Patch Availability(3)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| nuget | Microsoft.Native.Quic.MsQuic.OpenSSL @ 2.4.20 (fixes < 2.4.20) | — | ghsa |
| nuget | Microsoft.Native.Quic.MsQuic.OpenSSL @ 2.5.11 (fixes >= 2.5.0, < 2.5.11) | — | ghsa |
| nuget | Microsoft.Native.Quic.MsQuic.OpenSSL @ 2.6.1 (fixes >= 2.6.0, < 2.6.1) | — | ghsa |
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)
NuGet(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| Microsoft.Native.Quic.MsQuic.OpenSSL | 1.8.0 |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 16× in last 7d / 63× 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 it from the CNA feed. 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). Most recent first.
- 2026-11-02 22:08 UTCEG score recompute
- 2026-11-02 22:08 UTCGHSA enrichmentGHSA-w5f4-fx9m-m4q7 · GitHub severity CRITICAL
- 2026-11-02 16:43 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-11-01 20:38 UTCEG score recompute
- 2026-11-01 20:38 UTCGHSA enrichmentGHSA-w5f4-fx9m-m4q7 · GitHub severity CRITICAL
- 2026-11-01 16:33 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-11-01 08:00 UTCGHSA enrichmentGHSA-w5f4-fx9m-m4q7 · GitHub severity CRITICAL
- 2026-10-31 19:11 UTCEG score recompute
- 2026-10-31 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-30 17:41 UTCEG score recompute
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-29 16:14 UTCEG score recompute
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-28 14:46 UTCEG score recompute
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-27 00:17 UTCEG score recompute
- 2026-10-26 16:30 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-25 19:15 UTCEG score recompute
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-25 14:55 UTCEG score recompute
- 2026-10-24 17:40 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-23 16:14 UTCEG score recompute
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- 2026-10-22 16:33 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-22 14:42 UTCEG score recompute
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-21 13:14 UTCEG score recompute
- 2026-10-20 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-20 11:37 UTCEG score recompute
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-19 12:58 UTCEG score recompute
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-18 05:08 UTCEG score recompute
- 2026-10-17 16:33 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-17 10:03 UTCEG score recompute
- 2026-10-16 16:40 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-16 08:35 UTCEG score recompute
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-15 07:07 UTCEG score recompute
- 2026-10-14 16:31 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
- 2026-10-14 03:00 UTCEG score recompute
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-12 16:39 UTCEG score recompute
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-11 20:15 UTCEG score recompute
- 2026-10-11 18:17 UTCEG score recompute
- 2026-10-11 14:09 UTCEG score recompute
- 2026-10-11 13:47 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-10 21:38 UTCEG score recompute
- 2026-10-10 19:59 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-09 20:51 UTCEG score recompute
- 2026-10-09 20:06 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-08 20:04 UTCEG score recompute
- 2026-10-08 17:11 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-08 03:32 UTCEG score recompute
- 2026-10-07 23:47 UTCEPSS rescoreEPSS 1.0% · 61st percentile
- 2026-10-06 18:32 UTCEG score recompute
- 2026-10-06 17:47 UTCEG score recompute
- 2026-10-06 15:27 UTCEG score recompute
- 2026-10-06 14:30 UTCEG score recomputeFirst assessed: 9.1 CRITICAL
- 2026-10-06 14:29 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same CWE)
Same product
3 shownNuGet:Microsoft.Native.Quic.MsQuic.OpenSSL
Frequently asked(5)
What is CVE-2026-105794?
When was the CVE record for CVE-2026-105794 published?
Is CVE-2026-105794 actively exploited?
What is the CVSS score of CVE-2026-105794?
How do I remediate CVE-2026-105794?
Dependency Blast Radius
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