PT-2026-67231 · Legion Of The Bouncy Castle · Bc-Fja+2

CVE-2026-59638 · Published 2026-08-03 · Updated 2026-08-03

NVD

CVSS v4.0

9.3

Critical

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/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

In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).

Exploit

Fix

Weakness Enumeration

CWE-297

Related Identifiers

CVE-2026-59638

Affected Products

Bc-Fja

Bc-Java

Bc-Lts-Java

References · 4

• 🔥 https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638 · Exploit
• https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b · Patch
• https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-59638 · Security Note