CVE-2026-59646
Description
A flaw was found in Bouncy Castle for Java. The DTLS (Datagram Transport Layer Security) handshake reassembler allocates buffers based on an unchecked 24-bit length value. A remote attacker could exploit this vulnerability by sending a specially crafted DTLS handshake message, leading to excessive memory allocation and a denial of service (DoS) condition.
Statement
This flaw has an Important impact. Bouncy Castle for Java's DTLS handshake reassembler allocates a buffer from an unchecked 24-bit length field, so a remote, unauthenticated attacker who sends a specially crafted DTLS handshake message can force excessive memory allocation and cause a denial of service. Only the Bouncy Castle TLS module (bctls) contains the affected code; Red Hat products that ship only the core provider (bcprov) or other Bouncy Castle modules are not affected. Within Red Hat's portfolio, the vulnerable module is bundled by Red Hat Fuse (via Apache CXF) and Red Hat Satellite.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory
If the incorrect calculation is used in the context of memory allocation, then the software may create a buffer that is smaller or larger than expected. If the allocated buffer is smaller than expected, this could lead to an out-of-bounds read or write (CWE-119), possibly causing a crash, allowing arbitrary code execution, or exposing sensitive data.
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