CVE-2026-17507

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-10-02. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 3 sources updated this week

Also known asEUVD-2026-91235 (ENISA EUVD) · GHSA-x7w3-c4mv-whm4 (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines 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: 0.4%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In Bouncy Castle for Java before 1.86, the MLS implementation (org.bouncycastle.mls) holds RFC 9420's uint32 leaf_index in a signed int, so a wire value with the top bit set decodes to a negative number. That is a legitimate encoding rather than malformed input, and it must still decode, since the MLS interop test vectors round-trip the full range. GroupKeySet.SecretTree.hasLeaf and Group.validateRemove compared the decoded value directly against the tree's leaf count, and a signed comparison treats any negative int as less than a positive bound, so an out-of-range sender passed the membership check. In the hasLeaf case the SenderData of an unprotected PrivateMessage could then drive LeafIndex.directPath through NodeIndex.parent() arithmetic that never reaches the tree root, growing the resulting node list without bound until the JVM exhausted its heap. A single small message from any current group member could therefore deny service to every other member of the group. Both comparisons now interpret the value as unsigned via Integer.toUnsignedLong, rejecting an out-of-range sender however it was encoded; well-formed leaf indices are unaffected.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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.
Exploitation0.4% × 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 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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
36th
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.GitHub Security Advisory CVSS
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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.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).

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

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 2, 2026

Last Modified

October 14, 2026

Advisory Details (2)

Auto-updated Oct 2, 2026
Patch available. Sources: github_commit.
GitHub commit

commit 1eb83471eb01 (bcgit/bc-java)

Fix landed in bcgit/bc-java commit 1eb83471eb01 — awaiting tagged release

https://github.com/bcgit/bc-java/commit/1eb83471eb01727bfdb944a5a46355cc77d55f44
Web page

CVE‐2026‐17507 · bcgit/bc-java Wiki · GitHub

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9017507

Vendor Advisories for CVE-2026-17507(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(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 70× 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. 1 repeat row among the latest 80 is merged into the row it repeats.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-11-01 09:32 UTCEG score recompute
  3. 2026-11-01 09:32 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH · GitHub CVSS 7.5
  4. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  5. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  6. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  7. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  8. 2026-10-27 19:52 UTCEG score recompute
  9. 2026-10-27 19:52 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH · GitHub CVSS 7.5
  10. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  11. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  12. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  13. 2026-10-25 14:46 UTCEG score recompute
  14. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  15. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  16. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  17. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  18. 2026-10-20 19:07 UTCEG score recompute
  19. 2026-10-20 19:07 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH · GitHub CVSS 7.5
  20. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  21. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  22. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  23. 2026-10-18 04:00 UTCEG score recompute
  24. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  25. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 26th percentile
Show 54 more
  1. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  2. 2026-10-14 19:07 UTCEG score recompute▼ 1.20
  3. 2026-10-14 19:06 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  4. 2026-10-14 19:04 UTCNVD updateCVSS v3 → 7.5
  5. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  6. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  7. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  8. 2026-10-12 16:28 UTCEG score recompute
  9. 2026-10-12 02:57 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  10. 2026-10-11 20:08 UTCEG score recompute
  11. 2026-10-11 17:21 UTCEG score recompute
  12. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  13. 2026-10-11 13:44 UTCEG score recompute
  14. 2026-10-11 13:44 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  15. 2026-10-11 00:29 UTCEG score recompute
  16. 2026-10-11 00:29 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  17. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  18. 2026-10-10 11:16 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  19. 2026-10-09 22:06 UTCEG score recompute
  20. 2026-10-09 22:06 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  21. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  22. 2026-10-09 08:55 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  23. 2026-10-08 19:45 UTCEG score recompute
  24. 2026-10-08 19:45 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  25. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  26. 2026-10-08 06:35 UTCEG score recompute
  27. 2026-10-08 06:35 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  28. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  29. 2026-10-07 17:26 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  30. 2026-10-07 03:48 UTCEG score recompute
  31. 2026-10-07 03:48 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  32. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  33. 2026-10-06 14:38 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  34. 2026-10-06 01:28 UTCEG score recompute
  35. 2026-10-06 01:28 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  36. 2026-10-06 01:28 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  37. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  38. 2026-10-05 12:15 UTCEG score recompute
  39. 2026-10-05 12:15 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  40. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  41. 2026-10-04 23:06 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  42. 2026-10-04 09:53 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  43. 2026-10-03 20:43 UTCEG score recompute
  44. 2026-10-03 20:43 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  45. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  46. 2026-10-03 07:31 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  47. 2026-10-02 18:20 UTCEG score recompute
  48. 2026-10-02 18:20 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  49. 2026-10-02 17:47 UTCEG score recompute
  50. 2026-10-02 17:47 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  51. 2026-10-02 14:45 UTCGHSA enrichmentGHSA-x7w3-c4mv-whm4 · GitHub severity HIGH
  52. 2026-10-02 08:27 UTCEG score recompute
  53. 2026-10-02 07:31 UTCEG score recomputeFirst assessed: 8.7 HIGH
  54. 2026-10-02 07:30 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-17507?
CVE-2026-17507 is a high-severity vulnerability; its CVE record was published on October 2, 2026. In Bouncy Castle for Java before 1.86, the MLS implementation (org.bouncycastle.mls) holds RFC 9420's uint32 leaf_index in a signed int, so a wire value with the top bit set decodes to a negative number. That is a legitimate encoding rather than malformed input, and it must still decode, since the…
When was the CVE record for CVE-2026-17507 published?
The CVE record for CVE-2026-17507 was published on October 2, 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 14, 2026; the record at its source may have been updated since.
Is CVE-2026-17507 actively exploited?
CVE-2026-17507 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-17507?
CVE-2026-17507 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-17507?
A fix for CVE-2026-17507 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-17507 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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