Improper Verification of Cryptographic Signature Affecting org.bouncycastle:bcprov-jdk15to18 package, versions [1.85,1.86)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-ORGBOUNCYCASTLE-20419451
- published4 Oct 2026
- disclosed3 Oct 2026
- creditBhargava Shastry
Introduced: 3 Oct 2026
NewCVE-2026-71891 (opens in a new tab)How to fix?
Upgrade org.bouncycastle:bcprov-jdk15to18 to version 1.86 or higher.
Overview
org.bouncycastle:bcprov-jdk15to18 is a Java implementation of cryptographic algorithms.
Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the BLS12_381BasicScheme.keyValidate path in BLS12_381BasicScheme.java. An attacker can be accepted as a signer in BLS aggregate verification by supplying an ECPoint built on a non-canonical ECCurve that shares BLS12-381’s field characteristic but forges a cofactor of 1. The vulnerable subgroup check trusts the point’s own curve object, so a point that is not actually on the canonical G1 curve can pass keyValidate and then contribute nothing to the pairing result. This lets an aggregate signature verify even though one of the listed public keys did not sign the message, causing phantom-signer acceptance in applications that construct authority-bearing keys from explicit curve objects.