CVE-2026-59640
OpenPGP CFB oracle in Bouncy Castle enables decryption and session-key recovery.
Is CVE-2026-59640 being exploited?
Not confirmed. CVE-2026-59640 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.22% probability of exploitation in the next 30 days.
How severe is CVE-2026-59640?
CVE-2026-59640 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-59640?
Yes. A fix has been recorded for CVE-2026-59640. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-59640 affect?
CVE-2026-59640 affects Bouncy Castle for Java < 1.85, Bouncy Castle for Java LTS < 2.73.12, BC-FJA (bcpg-fips) < 1.0.13, 2.0.13, 2.1.13. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-59640?
Upgrade Bouncy Castle Java and BC-FJA to the listed fixed versions immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Adaptive chosen-ciphertext oracle on OpenPGP CFB allows decryption of messages and recovery of symmetric/session keys.
Immediate action required
- affected>= 1.0.0 and < 1.0.13
- affected>= 2.0.0 and < 2.0.13
- affected>= 2.1.0 and < 2.1.13
- affected< 1.85
- affected>= 2.73.0 and < 2.73.12
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.