CVE-2026-5588
Description
A flaw was found in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix. The PKIX draft CompositeVerifier implementation improperly accepts an empty signature sequence as a valid cryptographic signature. This issue allows a remote attacker to bypass signature verification mechanisms, potentially compromising the authenticity and integrity of data.
Statement
To exploit this issue, an attacker needs to submit a crafted payload or token containing an empty signature sequence to an application using the CompositeVerifier for cryptographic validation. An attack typically requires the application to process this malformed data and improperly accept the empty sequence as a valid signature, bypassing standard verification checks.
The primary impact of this vulnerability is the compromise of data authenticity and integrity, allowing an attacker to forge digital signatures and impersonate trusted entities.
Mitigation
To mitigate this flaw, check that the signature sequence is not empty before passing any data to the CompositeVerifier for cryptographic validation. If the sequence is empty or null, explicitly reject the payload before it is processed.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Access Control,Integrity,Confidentiality
Technical Impact: Gain Privileges or Assume Identity; Modify Application Data; Execute Unauthorized Code or Commands
An attacker could gain access to sensitive data and possibly execute unauthorized code.
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