01 Record

CVE-2026-5588

PKIX draft CompositeVerifier accepts empty signature sequence as valid.

MediumPUBLISHEDCNA: bcorg

CNA base score6.3 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber

View raw JSON

02 Description

PKIX draft CompositeVerifier accepts empty signature sequence as valid.

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.64% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 48.2% of scored records. A rank, not a probability.

NVD base score

6.3 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/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:X/AU:X/R:X/V:X/RE:X/U:Amber

NVD analysis status

Awaiting Analysis. NVD last modified this record on 2026-09-02.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-04-15 09:06Z4 MO AGO

Last updated

2026-09-02 12:04Z2 DAYS AGO

Reserved

2026-04-04

Assigning CNA

bcorg

Record state

PUBLISHED

Severity

Medium (CVSS 6.3)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/U:Amber

Weaknesses

CWE-327Use of a Broken or Risky Cryptographic AlgorithmClass
CWE-347Improper Verification of Cryptographic SignatureBase

Data version

5.2

Document digest

5affc64c43e30d91fd238b7a960c79882b6c12783a8413984da21e4d61c9fc9b

05 Affected products

VendorProductVersionsPlatforms

Legion of the Bouncy Castle Inc.BC-JAVA1.67 to < 1.80.2, 1.81 to < 1.81.1, 1.82 to < 1.84all

Legion of the Bouncy Castle Inc.BCPKIX-FIPS2.0.6 to < 2.0.11, 2.1.7 to < 2.1.11All

Legion of the Bouncy Castle Inc.BCPIX-LTS2.73.7 to < 2.73.11All

06 References

github.comhttps://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905588vendor-advisory
github.comhttps://github.com/bcgit/bc-java/commit/656bae0dbd9b1521f840521ff786e78749fe3057patch
access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-5588vdb-entryx_refsource_REDHAT
bugzilla.redhat.comRHBZ#2458634https://bugzilla.redhat.com/show_bug.cgi?id=2458634issue-trackingx_refsource_REDHAT
security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5588.jsonx_sadp-csaf-vex
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:53644vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18054vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18055vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60247vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60249vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60248vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60239vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60251vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60246vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60250vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60252vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60259vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60254vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:60256vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:14276vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:14272vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:13631vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:53806vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18059vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:21772vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17668vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:11720vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:11721vendor-advisoryx_refsource_REDHAT

01 Record index

CVE-2026-5588

02 Description

03 Exploitation and scoring

04 Metadata

05 Affected products

06 References

02 Records

CVE-2026-5588

02 Description

03 Exploitation and scoring

04 Metadata

05 Affected products

06 References