Exposure of the message authentication key through the encryption keystream in the stream mode of IesEngine (an IesEngine constructed without a block cipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has observed one encrypted message with known plaintext to forge shorter messages of their choosing that the recipient accepts as authentic, via a crafted ciphertext and MAC tag, because the MAC key was taken from the key derivation output directly after a keystream as long as the message, while the derivation input depends only on the static key pair and fixed parameters. The keystream revealed by that one message therefore contains the MAC key for every sufficiently shorter message.
CVE-2026-16001
“—” beside the score: it is equal to NVD's CVSS score.
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.2% (4th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-91206 (ENISA EUVD) · GHSA-43qj-h4fh-p2h4 (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 34EG Risk 34/100
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)Severity75% × 45%Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.2% × 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: 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, then apply it. - EPSS PROB
- 0.2%
- EPSS %ILE
- 4th
- 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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.2% 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 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.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. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.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.
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, then apply it.
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.
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. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.
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 2, 2026
Last Modified
October 27, 2026
Advisory Details (2)
Auto-updated Oct 2, 2026commit f881400b7611 (bcgit/bc-csharp)
Fix landed in bcgit/bc-csharp commit f881400b7611 — awaiting tagged release
https://github.com/bcgit/bc-csharp/commit/f881400b761134160ec2a05fd27c3e569453788dCVE 2026 16001 · bcgit/bc-csharp Wiki · GitHub
https://github.com/bcgit/bc-csharp/wiki/CVE-2026-16001Vendor Advisories for CVE-2026-16001(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 10× in last 7d / 65× 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.
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. 2 repeat rows among the latest 79 are merged into the row they repeat.
- 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-27 16:47 UTCEG score recompute▼ 0.70
- 2026-10-27 16:47 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-27 16:45 UTCNVD updateCVSS v3 → 7.5
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-10-25 14:47 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-20 19:07 UTCEG score recompute
- 2026-10-20 19:07 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-18 04:01 UTCEG score recompute
- 2026-10-17 18:08 UTCEG score recompute
- 2026-10-17 18:08 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
Show 52 moreShow fewer
- 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-12 16:31 UTCEG score recompute
- 2026-10-12 04:16 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-11 20:09 UTCEG score recompute
- 2026-10-11 17:22 UTCEG score recompute
- 2026-10-11 15:40 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-11 14:54 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-11 03:09 UTCEG score recompute
- 2026-10-11 03:08 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-10 14:33 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-10 02:01 UTCEG score recompute
- 2026-10-10 02:01 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-09 13:28 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-09 00:56 UTCEG score recompute
- 2026-10-09 00:56 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-08 12:24 UTCEG score recompute
- 2026-10-08 12:24 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-07 23:43 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-07 11:11 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-06 22:39 UTCEG score recompute
- 2026-10-06 22:39 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-06 10:07 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-05 21:35 UTCEG score recompute
- 2026-10-05 21:34 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-05 08:59 UTCEG score recompute
- 2026-10-05 08:59 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-04 20:27 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-04 07:55 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-03 19:23 UTCEG score recompute
- 2026-10-03 19:23 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-03 06:52 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-02 18:20 UTCEG score recompute
- 2026-10-02 18:20 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-02 18:00 UTCEG score recompute
- 2026-10-02 18:00 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-02 14:45 UTCGHSA enrichmentGHSA-43qj-h4fh-p2h4 · GitHub severity HIGH
- 2026-10-02 07:25 UTCEG score recompute
- 2026-10-02 07:06 UTCEG score recomputeFirst assessed: 8.2 HIGH
- 2026-10-02 07:05 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-16001?
When was the CVE record for CVE-2026-16001 published?
Is CVE-2026-16001 actively exploited?
What is the CVSS score of CVE-2026-16001?
How do I remediate CVE-2026-16001?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-16001
Is Your Infrastructure Affected by CVE-2026-16001?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.