CVE-2026-71884

HIGHPre-NVD 8.28.2
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (16th 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-2026-95586 (ENISA EUVD) · GHSA-qgfp-x9w9-pwj2 (GitHub Security Advisories)Source: ENISA EUVD

8.2EG
EchelonGraph verdictPlan mitigationNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, 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 (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 8.2Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

The CVE record's CNA (Legion of the Bouncy Castle Inc.) lists Legion of the Bouncy Castle Inc. BC-LTS-JAVA versions 2.73.4 up to but not including 2.73.13 as affected. No release containing a fix is confirmed on record.

In Bouncy Castle for Java LTS before 2.73.13, the native one-shot CTR packet cipher did not check that the requested input length fitted the counter space the IV left. In CTR mode the IV and the block counter share one 16-byte block, so an IV of 13 to 15 bytes leaves a counter of only 1 to 3 bytes, addressing 256, 65536 or 16777216 blocks respectively. Given a longer input the counter wrapped and the keystream repeated from the start of the same packet, and the call then returned the full input length as though every byte had been correctly transformed. Two segments of the message were therefore encrypted under the same keystream, so their plaintexts can be recovered from the ciphertext alone, without the key, while the caller saw neither an exception nor a short length to indicate it. The streaming implementation validates at init and again while processing, and the portable AESCTRPacketCipher rejects such a request with "Counter in CTR/SIC mode out of range.", but the native one-shot path has a single entry point and performed no counter-range validation there. It now preflights the IV-derived counter range and rejects an over-long request before any output is written, so the operation is failure-atomic and never reports success for bytes it did not correctly transform. A counter of four bytes or more cannot be exhausted by a Java int length and is unaffected, as is a full 16-byte IV, where the counter range is the caller's responsibility. Bouncy Castle for Java (bcprov) is not affected, as it ships no native implementations.

CVSS v3
8.2
EG Score
8.2HIGHmedium confidence
EG Risk
52
EG Risk 52/100

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)
Severity82% × 45%
Impact severity (EG Severity): CVSS 8.2 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.
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 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: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, 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.
EPSS PROB
0.3%
EPSS %ILE
16th
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 (8.2): severity, escalated by confirmed exploitation. This CVE's 8.2 is its impact severity (EG Severity), not escalated.

EG Severity
8.2 HIGHCVSS-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
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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: 14 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).

No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, 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.

Exploitation none (CISA Vulnrichment) · Automatable yes (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)14 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 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 9, 2026

Last Modified

October 15, 2026

Advisory Details (1)

Auto-updated Oct 9, 2026
No fix on record yet.
Web page

CVE‐2026‐71884 · bcgit/bc-java Wiki · GitHub

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071884

Vendor Advisories for CVE-2026-71884(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 9× in last 7d / 49× 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.

  1. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  2. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  3. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  4. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  5. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  6. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  7. 2026-10-27 21:08 UTCEG score recompute
  8. 2026-10-27 21:08 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  9. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  10. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  11. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  12. 2026-10-25 14:07 UTCEG score recompute
  13. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  14. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  15. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  16. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
  17. 2026-10-20 18:36 UTCEG score recompute
  18. 2026-10-20 18:36 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  19. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  20. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  21. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  22. 2026-10-18 03:16 UTCEG score recompute
  23. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  24. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  25. 2026-10-15 17:27 UTCEG score recompute
Show 24 more
  1. 2026-10-15 17:27 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  2. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  3. 2026-10-15 16:23 UTCEG score recompute
  4. 2026-10-15 16:22 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  5. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  6. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  7. 2026-10-13 08:25 UTCEG score recompute
  8. 2026-10-13 08:24 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  9. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  10. 2026-10-12 15:42 UTCEG score recompute
  11. 2026-10-11 19:28 UTCEG score recompute
  12. 2026-10-11 18:48 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  13. 2026-10-11 16:43 UTCEG score recompute
  14. 2026-10-11 14:03 UTCEG score recompute
  15. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  16. 2026-10-11 06:20 UTCEG score recompute
  17. 2026-10-11 06:19 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  18. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
  19. 2026-10-10 17:49 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  20. 2026-10-10 05:23 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  21. 2026-10-09 16:55 UTCGHSA enrichmentGHSA-qgfp-x9w9-pwj2 · GitHub severity HIGH
  22. 2026-10-09 10:47 UTCEG score recompute
  23. 2026-10-09 09:49 UTCEG score recomputeFirst assessed: 8.2 HIGH
  24. 2026-10-09 09:48 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-71884?
CVE-2026-71884 is a high-severity vulnerability; its CVE record was published on October 9, 2026. In Bouncy Castle for Java LTS before 2.73.13, the native one-shot CTR packet cipher did not check that the requested input length fitted the counter space the IV left. In CTR mode the IV and the block counter share one 16-byte block, so an IV of 13 to 15 bytes leaves a counter of only 1 to 3 bytes,…
When was the CVE record for CVE-2026-71884 published?
The CVE record for CVE-2026-71884 was published on October 9, 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 15, 2026; the record at its source may have been updated since.
Is CVE-2026-71884 actively exploited?
CVE-2026-71884 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (16th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-71884?
CVE-2026-71884 has a CVSS base score of 8.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-71884?
No fix for CVE-2026-71884 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's CNA (Legion of the Bouncy Castle Inc.) lists Legion of the Bouncy Castle Inc. BC-LTS-JAVA versions 2.73.4 up to but not including 2.73.13 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-71884 are linked in the Vendor Advisories panel on this page.

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