CVE-2026-58063 BCFKS keystore load honours unbounded KDF cost from untrusted file
Attackers can cause denial of service by providing a keystore file with an unbounded key derivation function cost, affecting Bouncy Castle for Java users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-58063?
CVE-2026-58063 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, and only if a user opens a file or follows a link.
Official description
In Bouncy Castle for Java before 1.85, BCFKS keystore load honours unbounded KDF cost from untrusted file. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bc-fips 1.0.2.7 (1.0.X series), 2.0.2 (2.0.X series) and 2.1.3 (2.1.X series).
Weakness: CWE-770
Which versions are affected by CVE-2026-58063?
It affects 3 products.
Products include Bouncycastle Bc-Java, Bouncycastle Bouncy Castle for Java Lts, Bouncycastle Fips Java Api.
How do I fix CVE-2026-58063?
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-2026-58063 being exploited?
There is no known exploitation of CVE-2026-58063 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-NP49753, CLEANSTART-2026-QX66145, CLEANSTART-2026-RD05519, CLEANSTART-2026-TG84112, CLEANSTART-2026-WM89566, DEBIAN-CVE-2026-58063 and 2 more.