CVE-2026-18036 Bouncy Castle - Timing Side-Channel Information Disclosure

Bouncy Castle for Java < 1.86 contains a timing side-channel vulnerability caused by secret-dependent integer division in NTRU polynomial reduction, letting attackers recover private key information via timing analysis, exploit requires precise timing measurement.

CVSS base score 8.2 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.28% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Timing Side-Channel Information Disclosure
Impact
Information Disclosure
CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
Published
2 October 2026
Updated
15 October 2026
Weakness
CWE-208

Vendor fix

Update to version 1.86 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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