CVE-2026-71891 Bouncy Castle - Broken Access Control

Bouncy Castle for Java < 1.86 contains a broken access control caused by improper validation of public keys on non-canonical ECCurves in BLS12_381BasicScheme, letting attackers forge phantom signers in aggregate signature verification, exploit requires application to accept ECPoints on explicit non-canonical curves.

CVSS base score 7.1 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.17% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Broken Access Control
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/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
3 October 2026
Updated
15 October 2026
Weakness
CWE-347

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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