HighCVE-2026-5598

Legion of the Bouncy Castle BC-JAVA: Covert Timing Channel (CVE-2026-5598)

Published 15.04.2026Last modified 26.10.2026Sources: BSI, Red Hat, CVE.org, OSV, EUVD

What is affected, what to do

Covert timing channel vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA core on all (core modules).

Update Legion of the Bouncy Castle BC-JAVA to version 1.80.2, Legion of the Bouncy Castle BC-JAVA to version 1.81.1, Legion of the Bouncy Castle BC-JAVA to version 1.84.

Affected: Legion of the Bouncy Castle BC-JAVA lt 1.71..1.80.2
Legion of the Bouncy Castle BC-JAVA lt 1.81..1.81.1
Legion of the Bouncy Castle BC-JAVA lt 1.82..1.84
Fixed in: Legion of the Bouncy Castle BC-JAVA 1.80.2
Legion of the Bouncy Castle BC-JAVA 1.81.1
Legion of the Bouncy Castle BC-JAVA 1.84

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Metrics

8.9

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v4

7.5

CVSS v3

Severity High on the scale from 0 to 10.

Source: BSI, Red Hat, CVE.org, OSV, EUVD

0.9 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 59.5

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 89.08 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 8.9 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.5
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 8.9
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.9 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 59.5; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 15.04.2026
CISA assessment (SSVC): Exploitation: none known · automatable · Technical impact: total; Source: CISA Vulnrichment, as of 15 April 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-385, CWE-385

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

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 affects BC-JAVA: from 1.71 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84.

Source: BSI WID Portal, BSI CSAF, redhat_csaf, NVD (NIST), cvelistv5, OSV (Open Source Vulnerabilities), CVE.org (MITRE), ENISA EUVD

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Legion of the Bouncy Castle Inc.	BC-JAVA	`1.71 – < 1.80.2` `1.82 – < 1.84` `1.81 – < 1.81.1`	`1.80.2` `1.84` `1.81.1`
Oracle	Fusion Middleware	`12.2.1.4.0` `8.5.8` `4.0.0-4.5.5` `14.1.1.0.0` `14.1.2.1.0` `14.1.2.0.0` `15.1.1.0.0` `3.0.0-3.2.21` `27.0.0`	— — — — — — — — —
Red Hat	JBoss Enterprise Application Platform	`7.4` `7.4.24`	— —
maven	org.bouncycastle:bcprov-jdk14	`1.81`	—
maven	org.bouncycastle:bcprov-jdk15to18	`1.73` `1.72` `1.79` `1.71` `1.78` `1.74` `1.75` `1.80` `1.77` `1.78.1` `1.76`	— — — — — — — — — — —
maven	org.bouncycastle:bcprov-jdk18on	`1.83` `1.82`	— —

Vendors and products

Weakness classes (CWE)

CWE-385Covert Timing Channel
Base
Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.
Entry at MITRE CWE-385
CWE-385Covert Timing Channel
Base
Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.
Entry at MITRE CWE-385

References & sources

NVD (NIST)vuln/detail/CVE-2026-5598advisory
github.combcgit/bc-java/commit/8692e6b2b191fc4aafa32545c7a78bdb9bf110c5web, Patch
github.combcgit/bc-java/commit/94abbd56413dfdac651fd878bc60253871ef5e87web, Patch
github.combcgit/bc-javapackage
github.combcgit/bc-java/wiki/CVE‐2026‐5598web, Vendor advisory
github.combcgit/bc-java/wiki/CVE-2026-5598web
access.redhat.comsecurity/cve/CVE-2026-5598Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2458635Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-5598.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:12267Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:18054Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:18055Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:12269Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:18059Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:53644Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:53806Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:53645Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:53646Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

18.09.2026Record modifiedRed Hat ADP

New references:

Show 4 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/5xxx/CVE-2026-5598.json">CVE-2026-5598</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:53645
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:53646
Reference	removed	https://access.redhat.com/errata/RHSA-2026:53806	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

10.09.2026Record modifiedbcorg

New references:

Show 6 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/bcgit/bc-java/commit/8692e6b2b191fc4aafa32545c7a78bdb9bf110c5
Reference	added	—	https://github.com/bcgit/bc-java/commit/94abbd56413dfdac651fd878bc60253871ef5e87
Reference	added	—	https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905598
Reference	removed	https://github.com/bcgit/bc-java/commit/8692e6b2b191fc4aafa32545c7a78bdb9bf110c5	—
Reference	removed	https://github.com/bcgit/bc-java/commit/94abbd56413dfdac651fd878bc60253871ef5e87	—
Reference	removed	https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905598	—

Source identifier: 91579145-5d7b-4cc5-b925-a0262ff19630

10.09.2026Record modifiedRed Hat ADP

New references:

and 6 more references

Show 21 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/5xxx/CVE-2026-5598.json">CVE-2026-5598</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:12267
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:12269
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:18054
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:18055
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:18059
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:53644
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:53806
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-5598
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2458635
Reference	added	—	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5598.json
Reference	removed	https://access.redhat.com/errata/RHSA-2026:12267	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:12269	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:18054	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:18055	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:18059	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:53644	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:53806	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-5598	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2458635	—
Reference	removed	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5598.json	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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