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CVE-2026-5598 — bcprov-jdk15to18

Fix: bcgit/bc-java@8692e6b

CVE-2026-5598 is a CWE-385 vulnerability in org.bouncycastle:bcprov-jdk15to18. A fix is available for org.bouncycastle:bcprov-jdk15to18 — see the affected versions and patch details below.

Non-constant time comparisons risk private key leakage in FrodoKEM.

Also known asGHSA-p93r-85wp-75v3
Published
Updated
Affected
5 pkgs
Patched
5 / 5
Exploits
None indexed
Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-5598.

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs60th percentile — riskier than 60% of all scored CVEsHighest risk
0.00%0.49%0.97%1.46%0.0%0.9%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

5 pkgs affected
☕org.bouncycastle:bcprov-jdk15to18☕org.bouncycastle:bcprov-jdk14☕org.bouncycastle:bcprov-jdk18on☕org.bouncycastle:bcprov-jdk18on☕org.bouncycastle:bcprov-jdk18on

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Covert timing channel vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA core on all (core modules). This vulnerability is associated with program files FrodoEngine.Java.

This issue only affects users of the FrodoKEM algorithm involved in the decryption of encapsulations.

This issue affects BC-JAVA: from 1.71 to 1.80.1, 1.81, 1.82 to 1.83.

Fixed versions: 1.80.2, 1.81.1, 1.84

Affected Packages

5 total 5 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.bouncycastle:bcprov-jdk15to18≥ 1.71&&< 1.80.21.80.2org.bouncycastle:bcprov-jdk15to18:1.80.2
☕Mavenorg.bouncycastle:bcprov-jdk14≥ 1.71&&< 1.841.84org.bouncycastle:bcprov-jdk14:1.84
☕Mavenorg.bouncycastle:bcprov-jdk18on≥ 1.82&&< 1.841.84org.bouncycastle:bcprov-jdk18on:1.84
☕Mavenorg.bouncycastle:bcprov-jdk18on≥ 1.81&&< 1.841.84org.bouncycastle:bcprov-jdk18on:1.84
☕Mavenorg.bouncycastle:bcprov-jdk18on≥ 1.71&&< 1.80.21.80.2org.bouncycastle:bcprov-jdk18on:1.80.2

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.bouncycastle:bcprov-jdk15to18, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.bouncycastle:bcprov-jdk15to18 to 1.80.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-5598 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

To exploit this issue, an unauthenticated attacker needs to send highly specific, malformed ciphertexts to the target server. These payloads are used to interact with the private key of the server in a way that the vulnerable, non-constant time code paths are triggered during the verification step. An attack typically…

Workaround published by Red Hat
To mitigate this vulnerability, implement aggressive rate limiting and anomaly detection, specifically looking for unusual, high-frequency cryptographic handshake failures or anomalous traffic patterns targeting endpoints that handle key exchanges in the network logs.
Source: Red Hat security advisory for CVE-2026-5598 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat JBoss Enterprise Application Platform 7.4.25bcprov-jdk12RHSA-2026:53806
Red Hat JBoss Enterprise Application Platform 7.4.25org.bouncycastle/bcprov-jdk18on:1.84.0.redhat-00001RHSA-2026:12269
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7eap7-bouncycastle-0:1.84.0-1.redhat_00001.1.el7eapRHSA-2026:12267
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7eap7-activemq-artemis-0:2.16.0-22.redhat_00057.1.el7eapRHSA-2026:53644
Red Hat JBoss Enterprise Application Platform 8.1.6.GAorg.bouncycastle/bcprov-jdk18on:1.84.0.redhat-00001RHSA-2026:18059
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8eap8-bouncycastle-0:1.84.0-1.redhat_00001.1.el8eapRHSA-2026:18054
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9eap8-bouncycastle-0:1.84.0-1.redhat_00001.1.el9eapRHSA-2026:18055

Frequently Asked Questions

Covert timing channel vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA core on all (core modules). This vulnerability is associated with program files FrodoEngine.Java. This issue only affects users of the FrodoKEM algorithm involved in the decryption of encapsulations. This issue affects BC-JAVA: from 1.71 to 1.80.1, 1.81, 1.82 to 1.83. Fixed versions: 1.80.2, 1.81.1, 1.84
O3 Security · Impact-Aware SCA

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CVE-2026-5598: bcprov-jdk15to18 — Fixed in 1.80.2