UBUNTU-CVE-2026-18040

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

CVE-2026-71890 MLS external commit can remove an arbitrary group member

In Bouncy Castle for Java before 1.86, validation of an MLS RFC 9420 external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to d...

CVE-2026-71890 MLS external commit can remove an arbitrary group member

In Bouncy Castle for Java before 1.86, validation of an MLS RFC 9420 external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to d...

EUVD-2026-92006

In Bouncy Castle for Java before 1.86, validation of an MLS RFC 9420 external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to d...

CVE-2026-71890 MLS external commit can remove an arbitrary group member

In Bouncy Castle for Java before 1.86, validation of an MLS RFC 9420 external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to d...

CVE-2026-71890

Bouncy Castle for Java versions before 1.86 are vulnerable to an authorization flaw in the MLS (RFC 9420) protocol implementation. The org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals method fails to verify that a Remove proposal in an external commit belongs to the joiner. Thi...

CVE-2026-71890

In Bouncy Castle for Java before 1.86, validation of an MLS RFC 9420 external commit's proposal list, org.bouncycastle.mls.protocol.Group.validateExternalCachedProposals, counted the proposals by type and bounded the removed leaf index but never established that the removed leaf had anything to d...

EUVD-2026-92005

In Bouncy Castle for Java before 1.86, BLS12381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field...

CVE-2026-71891

In Bouncy Castle for Java before version 1.86 , the BLS12_381BasicScheme.keyValidate function (and associated components like BLSPublicKeyParameters) failed to properly validate public keys. It accepted keys built on a foreign ECCurve that shared the same field characteristic as BLS12-381 . The r...

CVE-2026-71891 BLS12-381 key validation accepts a public key built on a foreign curve

In Bouncy Castle for Java before 1.86, BLS12381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field...

CVE-2026-71891 BLS12-381 key validation accepts a public key built on a foreign curve

In Bouncy Castle for Java before 1.86, BLS12381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field...

CVE-2026-71891 BLS12-381 key validation accepts a public key built on a foreign curve

In Bouncy Castle for Java before 1.86, BLS12381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field...

CVE-2026-71891

In Bouncy Castle for Java before 1.86, BLS12381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key built on a foreign ECCurve that merely shares BLS12-381's field...

CVE-2026-18040 HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-dependent fixed-weight sampler

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

EUVD-2026-92004

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

CVE-2026-18040 HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-dependent fixed-weight sampler

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

CVE-2026-18040

Bouncy Castle for Java versions before 1.86 are vulnerable to the leakage of secret-derived data within the HQC implementation. The root cause involves two side channels: GF(2^8) arithmetic utilizing lookup tables indexed by field elements (making touched cache lines a function of the operand), a...

CVE-2026-18040 HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-dependent fixed-weight sampler

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

CVE-2026-18040

In Bouncy Castle for Java before 1.86, HQC leaked secret-derived data through two side channels: its GF2^8 arithmetic used lookup tables indexed by field elements, making the cache line touched a function of the operand, and its fixed-weight support sampler left its duplicate scan as soon as a...

CVE-2026-71885

In Bouncy Castle for Java versions before 1.86 , the Messaging Layer Security (MLS, RFC 9420) implementation failed to bind an X.509 credential to a LeafNode's signature_key . Because the X.509 certificate chain was stored but never parsed or validated, the end-entity certificate's public key was...