CVE-2026-59647 CRMF/CMP password-MAC honours unbounded iteration count
An attacker can cause denial of service in Bouncy Castle Java libraries by exploiting unbounded iteration counts in CRMF/CMP password-MAC processing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59647?
CVE-2026-59647 is a medium-severity denial of service vulnerability in Bouncycastle Bc-Java, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In Bouncy Castle for Java before 1.85, CRMF/CMP password-MAC honours unbounded iteration count. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.12 (1.0.X series), 2.0.12 (2.0.X series) and 2.1.12 (2.1.X series).
Weakness: CWE-770
Which versions are affected by CVE-2026-59647?
It affects 3 products.
Products include Bouncycastle Bc-Java, Bouncycastle Bcpkix-Fips, Bouncycastle Bouncy Castle for Java Lts.
How do I fix CVE-2026-59647?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-59647 being exploited?
There is no known exploitation of CVE-2026-59647 in the wild and no public exploit code.
Other vulnerabilities in Bouncycastle Bc-Java
- CVE-2007-6721 Legion of the Bouncy Castle Java Cryptography API Bleichenbacher Oracle Vulnerability
- CVE-2018-1000613 Deserialization of Untrusted Data in Bouncy castle
- CVE-2026-58062 Stapled OCSP response accepted without binding to the checked certificate
- CVE-2026-59638 JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
- CVE-2026-59650 MTI/A0 DH agreement exponentiates unvalidated peer value
Sources
Also known as CLEANSTART-2026-FU52429, CLEANSTART-2026-IZ67766, CLEANSTART-2026-JP93433, CLEANSTART-2026-PX22930, CLEANSTART-2026-VT41393, DEBIAN-CVE-2026-59647 and 2 more.