Improper input validation in DHAgreement.CalculateAgreement (MTI/A0 two-pass Diffie-Hellman) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an on-path attacker to make the local party compute an agreed value the attacker already knows, defeating the key authentication MTI/A0 is meant to provide. It also allows a malicious peer to learn the local static private key modulo the small factors of p-1, and to recover it entirely in groups with many such factors. The attack uses a crafted out-of-range or small-order ephemeral value, and works because that value is raised to the static private key without the range and subgroup-membership checks applied to DH public keys. Only applications that call DHAgreement directly are affected.
CVE-2026-63569
“—” beside the score: it is equal to NVD's CVSS score.
This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.3% (25th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-91220 (ENISA EUVD) · GHSA-m2m9-m35w-rfxg (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMmedium confidence
- EG Risk
- 44EG Risk 44/100
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)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.4% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it. - EPSS PROB
- 0.3%
- EPSS %ILE
- 25th
- 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 (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS. 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; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.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; Attend at high (mission-essential systems).
An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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)3 days if the affected system is publicly exposed; 60 days if it is not.
No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (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 2, 2026
Last Modified
October 28, 2026
Advisory Details (2)
Auto-updated Oct 2, 2026commit fe236ad207c5 (bcgit/bc-csharp)
Fix landed in bcgit/bc-csharp commit fe236ad207c5 — awaiting tagged release
https://github.com/bcgit/bc-csharp/commit/fe236ad207c5960eeae1ebb6560c783a3bb5b692CVE 2026 63569 · bcgit/bc-csharp Wiki · GitHub
https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63569Vendor Advisories for CVE-2026-63569(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 15× in last 7d / 123× 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.
Showing the most recent 100 of 144 refreshes 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 44 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.3% · 25th percentile
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-28 15:06 UTCEG score recompute▼ 2.60
- 2026-10-28 15:06 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-28 15:06 UTCNVD updateCVSS v3 → 6.5 · severity → MEDIUM
- 2026-10-28 12:10 UTCEG score recompute
- 2026-10-28 12:10 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-27 13:04 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-27 12:15 UTCEG score recompute
- 2026-10-27 12:15 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-26 13:10 UTCEG score recompute
- 2026-10-26 13:09 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-25 13:54 UTCEG score recompute
- 2026-10-25 13:54 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-24 14:47 UTCEG score recompute
- 2026-10-24 14:47 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
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- 2026-10-23 15:41 UTCEG score recompute
- 2026-10-23 15:41 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-22 16:34 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-21 16:35 UTCEG score recompute
- 2026-10-21 16:35 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-20 17:21 UTCEG score recompute
- 2026-10-20 17:21 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-20 07:06 UTCEG score recompute
- 2026-10-20 07:06 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-19 07:57 UTCEG score recompute
- 2026-10-19 07:56 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-18 08:49 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-18 03:23 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-17 06:27 UTCEG score recompute
- 2026-10-17 06:27 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-16 07:18 UTCEG score recompute
- 2026-10-16 07:17 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-15 06:13 UTCEG score recompute
- 2026-10-15 06:13 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
- 2026-10-14 01:50 UTCEG score recompute
- 2026-10-14 01:49 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-12 22:02 UTCEG score recompute
- 2026-10-12 22:01 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-12 15:49 UTCEG score recompute
- 2026-10-12 01:26 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-11 21:08 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-11 19:33 UTCEG score recompute
- 2026-10-11 16:50 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-11 16:48 UTCEG score recompute
- 2026-10-11 14:10 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-11 12:33 UTCEG score recompute
- 2026-10-11 12:32 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-11 08:15 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-11 03:55 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 23:37 UTCEG score recompute
- 2026-10-10 23:37 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-10 19:17 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 14:58 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 10:41 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 06:23 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-10 02:04 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 21:45 UTCEG score recompute
- 2026-10-09 21:44 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-09 17:27 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 13:05 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 08:46 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 04:23 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-09 00:05 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-08 19:48 UTCEG score recompute
- 2026-10-08 19:48 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-08 15:30 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-08 09:41 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-08 05:24 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-08 01:06 UTCEG score recompute
- 2026-10-08 01:06 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-07 20:48 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-07 16:09 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-07 11:51 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
- 2026-10-07 07:32 UTCGHSA enrichmentGHSA-m2m9-m35w-rfxg · GitHub severity CRITICAL
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Frequently asked(5)
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Dependency Blast Radius
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