CVE-2026-71885

CRITICALPre-NVD 9.29.2
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (9th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-92003 (ENISA EUVD) · GHSA-jch3-5j66-88vx (GitHub Security Advisories)Source: ENISA EUVD

9.2EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 9.2Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In Bouncy Castle for Java before 1.86, the Messaging Layer Security (MLS, RFC 9420) implementation did not bind an X.509 credential to a LeafNode's signature_key. LeafNode.verify() checked a leaf's signature against the signature_key carried in the leaf itself, while the credential's X.509 certificate chain was stored but never parsed or validated, so the end-entity certificate's public key was never required to match signature_key as RFC 9420 sec. 5.3 requires. A party could therefore present another party's certificate as its credential while signing the leaf, and the enclosing KeyPackage, with an unrelated key, and be accepted under that other party's identity through KeyPackage.verify() and the Group leaf-validation path. In a deployment that admits external commits without an independent credential-admission check, an unauthenticated attacker could be admitted under a victim's X.509 identity, evict the victim (resynchronization compares whole credentials rather than signing keys), derive the current epoch, decrypt subsequent group messages, and send messages accepted as the victim. TreeKEM.LeafNode now requires the end-entity certificate's subject public key, in the cipher suite's signature encoding, to equal signature_key for an X.509 credential and rejects the leaf otherwise, including an empty chain or a certificate whose key type does not match the cipher suite; certificate-chain and identity validation to a trust anchor remain the application's responsibility per RFC 9420 sec. 5.3.1. Deployments using only basic credentials are unaffected.

CVSS v3
9.2
EG Score
9.2CRITICALmedium confidence
EG Risk
41
EG 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)
Severity92% × 45%
Impact severity (EG Severity): CVSS 9.2 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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (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: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
9th
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 (9.2): severity, escalated by confirmed exploitation. This CVE's 9.2 is its impact severity (EG Severity), not escalated.

EG Severity
9.2 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
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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: 14 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).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)14 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 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 3, 2026

Last Modified

October 6, 2026

Advisory Details (2)

Auto-updated Oct 3, 2026
Patch available. Sources: github_commit.
GitHub commit

commit 77632a57edf3 (bcgit/bc-java)

Fix landed in bcgit/bc-java commit 77632a57edf3 — awaiting tagged release

https://github.com/bcgit/bc-java/commit/77632a57edf350a7b5751fca1a5052daffa8dab2
Web page

CVE‐2026‐71885 · bcgit/bc-java Wiki · GitHub

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071885

Vendor Advisories for CVE-2026-71885(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
bouncycastle1.72-2 ... 1.86-1 (6 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
bouncycastle1.80-3, 1.86-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
bouncycastle1.80-3
  • every version up to 1.86-1: fixed in 1.86-1
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 20× in last 7d / 138× 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 141 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 41 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 22:40 UTCEG score recompute
  2. 2026-11-01 22:40 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  3. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  4. 2026-10-31 20:46 UTCEG score recompute
  5. 2026-10-31 20:46 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  6. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  7. 2026-10-30 18:51 UTCEG score recompute
  8. 2026-10-30 18:51 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  9. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  10. 2026-10-29 16:57 UTCEG score recompute
  11. 2026-10-29 16:57 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  12. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  13. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  14. 2026-10-28 15:03 UTCEG score recompute
  15. 2026-10-28 15:03 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  16. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  17. 2026-10-27 13:09 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  18. 2026-10-27 03:16 UTCEG score recompute
  19. 2026-10-27 03:16 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  20. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  21. 2026-10-25 21:17 UTCEG score recompute
  22. 2026-10-25 21:17 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  23. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  24. 2026-10-25 14:07 UTCEG score recompute
  25. 2026-10-24 19:23 UTCEG score recompute
Show 75 more
  1. 2026-10-24 19:23 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  2. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  3. 2026-10-23 17:29 UTCEG score recompute
  4. 2026-10-23 17:29 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  6. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  7. 2026-10-22 15:34 UTCEG score recompute
  8. 2026-10-22 15:34 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  9. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  10. 2026-10-21 13:39 UTCEG score recompute
  11. 2026-10-21 13:39 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  12. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  13. 2026-10-20 11:44 UTCEG score recompute
  14. 2026-10-20 11:44 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  15. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  16. 2026-10-19 13:50 UTCEG score recompute
  17. 2026-10-19 13:50 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  18. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  19. 2026-10-18 11:54 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  20. 2026-10-18 03:16 UTCEG score recompute
  21. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  22. 2026-10-17 09:58 UTCEG score recompute
  23. 2026-10-17 09:58 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  24. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  25. 2026-10-16 08:02 UTCEG score recompute
  26. 2026-10-16 08:02 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  27. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  28. 2026-10-15 06:08 UTCEG score recompute
  29. 2026-10-15 06:08 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  30. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  31. 2026-10-14 01:45 UTCEG score recompute
  32. 2026-10-14 01:45 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  33. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  34. 2026-10-12 21:56 UTCEG score recompute
  35. 2026-10-12 21:56 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  36. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  37. 2026-10-12 15:42 UTCEG score recompute
  38. 2026-10-12 02:55 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  39. 2026-10-11 22:57 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  40. 2026-10-11 19:28 UTCEG score recompute
  41. 2026-10-11 18:59 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  42. 2026-10-11 16:43 UTCEG score recompute
  43. 2026-10-11 15:03 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  44. 2026-10-11 14:03 UTCEG score recompute
  45. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  46. 2026-10-11 11:07 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  47. 2026-10-11 07:08 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  48. 2026-10-11 03:11 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  49. 2026-10-10 23:11 UTCEG score recompute
  50. 2026-10-10 23:10 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  51. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  52. 2026-10-10 19:14 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  53. 2026-10-10 15:07 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  54. 2026-10-10 11:11 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  55. 2026-10-10 07:16 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  56. 2026-10-10 03:17 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  57. 2026-10-09 23:21 UTCEG score recompute
  58. 2026-10-09 23:21 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  59. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  60. 2026-10-09 19:26 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  61. 2026-10-09 15:30 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  62. 2026-10-09 11:33 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  63. 2026-10-09 07:30 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  64. 2026-10-09 03:34 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  65. 2026-10-08 23:38 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  66. 2026-10-08 19:42 UTCEG score recompute
  67. 2026-10-08 19:42 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  68. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  69. 2026-10-08 15:28 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  70. 2026-10-08 10:10 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  71. 2026-10-08 06:14 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  72. 2026-10-08 02:18 UTCEG score recompute
  73. 2026-10-08 02:18 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL
  74. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  75. 2026-10-07 22:22 UTCGHSA enrichmentGHSA-jch3-5j66-88vx · GitHub severity CRITICAL

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-71885?
CVE-2026-71885 is a critical-severity vulnerability; its CVE record was published on October 3, 2026. In Bouncy Castle for Java before 1.86, the Messaging Layer Security (MLS, RFC 9420) implementation did not bind an X.509 credential to a LeafNode's signature_key. LeafNode.verify() checked a leaf's signature against the signature_key carried in the leaf itself, while the credential's X.509…
When was the CVE record for CVE-2026-71885 published?
The CVE record for CVE-2026-71885 was published on October 3, 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 6, 2026; the record at its source may have been updated since.
Is CVE-2026-71885 actively exploited?
CVE-2026-71885 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-71885?
CVE-2026-71885 has a CVSS base score of 9.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-71885?
A fix for CVE-2026-71885 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-71885 are linked in the Vendor Advisories panel on this page.

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