CVE-2026-5598 | Non-constant time comparisons risk private key leakage in FrodoKEM.

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 1.80.1, from 1.82 before 1.84.

Published: 2026-04-15 Last update: 2026-05-19 Assigner: 91579145-5d7b-4cc5-b925-a0262ff19630 Source: 91579145-5d7b-4cc5-b925-a0262ff19630
NVD Status：Awaiting Analysis，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-5598 is rated Moderate Risk (40.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-5598

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-15 — 0.04% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-5598

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.9 4.0 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:U/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:P/AU:Y/R:X/V:X/RE:X/U:Red Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:H)
High confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:H)
High integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:U)
Unreported: no public PoC, no reported exploitation, and no known simplification tools.
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:P)
Present: impact meets IEC 61508 marginal, critical, or catastrophic safety consequence levels.
Automatable (supplemental) (AU:Y)
Yes: all four kill-chain steps (reconnaissance, weaponization, delivery, exploitation) can be automated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:RED)
Red: provider rates highest urgency.
 — — 91579145-5d7b-4cc5-b925-a0262ff19630

Weakness enumeration for CVE-2026-5598

GitHub Security Advisory for CVE-2026-5598

GHSA-p93r-85wp-75v3 · Severity: high · Ecosystem: maven — Bouncy Castle Has Covert Timing Channel Vulnerability

OS Trackers for CVE-2026-5598

vendor priority summary link
debian unimportant CVE-2026-5598 unimportant priority: Debian including 1 source packages (bouncycastle), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 4, resolved 1. https://security-tracker.debian.org/tracker/CVE-2026-5598
redhat high — https://access.redhat.com/security/cve/CVE-2026-5598
suse high — https://www.suse.com/security/cve/CVE-2026-5598/
ubuntu medium CVE-2026-5598 medium priority: Ubuntu including 1 source packages (bouncycastle), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needs-triage 7, ignored 1. https://ubuntu.com/security/CVE-2026-5598

Affected software / configurations for CVE-2026-5598

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-5598

cvelogic Threat Intelligence