CVE-2026-71884 Bouncy Castle - Cryptographic Vulnerability

Bouncy Castle for Java LTS before 2.73.13 contains a cryptographic vulnerability caused by lack of counter range validation in native one-shot CTR packet cipher, letting attackers recover plaintext from ciphertext due to keystream reuse, exploit requires crafted input with specific IV length.

CVSS base score 8.2 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.41% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Cryptographic Vulnerability
Impact
Information Disclosure
CVSS vector
CVSS:4.0/AV:N/AC:L/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
9 October 2026
Updated
15 October 2026
Weakness
CWE-323

Vendor fix

Update to version 2.73.13 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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