CVE-2026-59643Network attack vector

Signature-policy bypass via swallowed sanitization exception

Published Aug 3, 2026 · Updated Aug 3, 2026

Improper signature verification in Bouncy Castle for Java 1.81 through 1.84 allows remote attackers to accept policy-rejected signatures. OpenPGPMessageInputStream.OnePassSignatures.verify() catches the PGPSignatureException from sanitize() but falls through to cryptographic verification, marking a rejected signature as tested and correct. Reachability requires an application to process inline one-pass signatures through the high-level API; Bouncy Castle for Java FIPS bcpg-fips 2.0.12 is also affected, and acceptance requires a cryptographically valid or collision-forged signature from a trusted key.

CVSS severity8.7
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Bouncy Castle for Java 1.81 through 1.84 allows remote attackers to accept policy-rejected signatures. OpenPGPMessageInputStream.OnePassSignatures.verify() catches the PGPSignatureException from sanitize() but falls through to cryptographic verification, marking a rejected signature as tested and correct. Reachability requires an application to process inline one-pass signatures through the high-level API; Bouncy Castle for Java FIPS bcpg-fips 2.0.12 is also affected, and acceptance requires a cryptographically valid or collision-forged signature from a trusted key.

The record

CVE
CVE-2026-59643
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Legion of the Bouncy Castle Inc.
Product
Bouncy Castle Java
Classifications
CWE-347, T1553
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.81 <1.85

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Legion of the Bouncy Castle Inc. · Bouncy Castle Javaversion=1.81 <1.85
Legion of the Bouncy Castle Inc. · Bouncy Castle Java FIPSversion=2.0.12 <2.0.13

Published CVSS scores

8.7bcorgCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1553Subvert Trust Controls

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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