CVE-2026-59639

CMS verifySignatures returns true for SignedData with zero signers

HIGH

7.5

CVSS Score

Published: August 3, 2026 at 12:56 AM UTC

Updated: August 28, 2026 at 03:52 PM UTC

5 products affected across 2 vendorsBc JavaBouncy Castle for Java LtsBcpkix Fips

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Severity

HIGH7.5

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

In Bouncy Castle for Java before 1.85, CMS verifySignatures returns true for SignedData with zero signers. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.12 (1.0.X series), 2.0.12 (2.0.X series) and 2.1.12 (2.1.X series).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Bc Java · Bouncycastle

95%

v < 1.85

Affected range stops below 1.85, so it looks safe — our inference, not a vendor statement

Bcpkix Fips · Bouncycastle

95%

v < 1.0.122.0.7 ≤ v < 2.0.122.1.8 ≤ v < 2.1.12

Affected range stops below 1.0.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.0.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.1.12, so it looks safe — our inference, not a vendor statement

Bouncy Castle for Java Lts · Bouncycastle

95%

v ≤ 2.73.11

Bouncy Castle for Java FIPS (BC-FJA)· Legion of Bouncy Castlemaven

60%

1.0.0 ≤ v < 1.0.122.0.0 ≤ v < 2.0.122.1.0 ≤ v < 2.1.121.0.0 2.0.0 2.1.0

Affected range stops below 1.0.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.0.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.1.12, so it looks safe — our inference, not a vendor statement

BC Java · Legion of Bouncy Castlemaven

60%

v < 1.852.73.0 ≤ v < 2.73.122.73.0

Affected range stops below 1.85, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.73.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Source: cverecord

https://github.com/bcgit/bc-java/wiki/CVE-2026-59639

Patch

Source: cverecord

https://github.com/bcgit/bc-java/commit/99ddc6dcc6782e6a76b0dd587c77e62eb7096ad0

Vendor AdvisoryThird Party Advisory

Source: cverecord

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059639

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-347

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