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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
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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
0.77% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 55.5% 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 2026-10-26.
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 09:06Z6 MO AGO
Last updated
2026-09-18 12:04Z1 MO 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
97e2d77fb6d896c51161f58f8032ad22d29169f25da4328ab4a15e09a9663e74

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

07 Fixed in

Debian 12

  • bouncycastle
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • bouncycastle
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • bouncycastle
    Fixed in 1.86-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 25.10

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 18.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 20.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 24.04 LTS

  • bouncycastle
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.