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Vulnerability record · CVE-2026-59640 · published 3 August 2026

CVE-2026-59640: Bouncycastle bc-java observable discrepancy vulnerability

Bouncycastle · Bc Java

In Bouncy Castle for Java before 1.85, OpenPGP CFB quick-check oracle active on symmetric/session-key paths. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpg-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

8.7 CVSS 4.0 High EPSS 0.35% · top 74.4% CWE-203 · Observable discrepancy
8.7CVSS 4.0 base score
0.35%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
2References
28 Aug 2026Last modified by NVD

Description

In Bouncy Castle for Java before 1.85, OpenPGP CFB quick-check oracle active on symmetric/session-key paths. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpg-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/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:

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/bcgit/bc-java/commit/6b94b1c146cec1f565d9a85847fae511af77503e Patch
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059640 Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-59640), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.