CVE-2026-59640: CWE-203 Observable Discrepancy in Legion of the Bouncy Castle Inc. BC-JAVA
CVE-2026-59640 is a high-severity vulnerability in Bouncy Castle for Java (BC-JAVA) involving an OpenPGP CFB quick-check oracle on symmetric/session-key paths. This affects versions before 1.85, versions from 2.73.0 up to but not including 2.73.12, and certain FIPS series versions. The vulnerability is categorized under CWE-203 (Observable Discrepancy). No official patch or remediation level has been confirmed yet.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-59640) affects Bouncy Castle for Java implementations prior to version 1.85 and versions from 2.73.0 up to 2.73.12, as well as specific FIPS series versions. It involves an OpenPGP CFB quick-check oracle active on symmetric/session-key paths, which is classified under CWE-203 (Observable Discrepancy). The CVSS 4.0 base score is 8.7, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality. The vendor has not yet provided an official fix or remediation guidance. No known exploits are reported in the wild at this time.
Potential Impact
The vulnerability allows an attacker to leverage an oracle on symmetric/session-key paths in OpenPGP CFB mode, potentially leading to information disclosure due to observable discrepancies. The high CVSS score reflects significant confidentiality impact without requiring privileges or user interaction. However, no active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should monitor vendor communications for updates. No temporary or official fixes have been documented at this time.
CVE-2026-59640: CWE-203 Observable Discrepancy in Legion of the Bouncy Castle Inc. BC-JAVA
Description
CVE-2026-59640 is a high-severity vulnerability in Bouncy Castle for Java (BC-JAVA) involving an OpenPGP CFB quick-check oracle on symmetric/session-key paths. This affects versions before 1.85, versions from 2.73.0 up to but not including 2.73.12, and certain FIPS series versions. The vulnerability is categorized under CWE-203 (Observable Discrepancy). No official patch or remediation level has been confirmed yet.
CVSS v4.0
Score 8.7high
Affected software
Legion of the Bouncy Castle Inc.
BC-JAVA
Legion of the Bouncy Castle Inc.
BC-LTS-JAVA
Legion of the Bouncy Castle Inc.
BC-FJA
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-59640) affects Bouncy Castle for Java implementations prior to version 1.85 and versions from 2.73.0 up to 2.73.12, as well as specific FIPS series versions. It involves an OpenPGP CFB quick-check oracle active on symmetric/session-key paths, which is classified under CWE-203 (Observable Discrepancy). The CVSS 4.0 base score is 8.7, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality. The vendor has not yet provided an official fix or remediation guidance. No known exploits are reported in the wild at this time.
Potential Impact
The vulnerability allows an attacker to leverage an oracle on symmetric/session-key paths in OpenPGP CFB mode, potentially leading to information disclosure due to observable discrepancies. The high CVSS score reflects significant confidentiality impact without requiring privileges or user interaction. However, no active exploitation has been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should monitor vendor communications for updates. No temporary or official fixes have been documented at this time.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- bcorg
- Date Reserved
- 2026-07-06T06:58:29.263Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a6fe8f1bf32cb7a34b61c96
Added to database: 08/03/2026, 01:03:45 UTC
Last enriched: 08/10/2026, 15:25:27 UTC
Last updated: 09/16/2026, 22:01:36 UTC
Views: 40
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