CVE-2026-71892
published 2026-10-03CVE-2026-71892: In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients…
PriorityP337medium6.9CVSS 4.0
AVNACLATNPRNUINVCLVILVANSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUAmber
EPSS
0.17%
6.4th percentile
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).
Affected
17 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| ansible-automation-platform-27 | de-minimal-rhel9 | — | — |
| ansible-automation-platform-27 | de-supported-rhel9 | — | — |
| candlepinproject | candlepin | — | — |
| devspaces | jetbrains-ide-rhel9 | — | — |
| devspaces | openvsx-rhel9 | — | — |
| devspaces | pluginregistry-rhel9 | — | — |
| jboss-eap-7 | eap74-els-openjdk11-openshift-rhel8 | — | — |
| jboss-eap-7 | eap74-els-openjdk17-openshift-rhel8 | — | — |
| jboss-eap-7 | eap74-els-openjdk8-openshift-rhel8 | — | — |
| jenkins | jenkins | — | — |
| legion_of_the_bouncy_castle_inc | bc-fja | >= 2.0.7 < 2.0.13 | 2.0.13 |
| legion_of_the_bouncy_castle_inc | bc-fja | >= 2.1.0 < 2.1.13 | 2.1.13 |
| legion_of_the_bouncy_castle_inc | bc-java | >= 1.78 < 1.86 | 1.86 |
| ocp-tools-4 | jenkins-rhel8 | — | — |
| ocp-tools-4 | jenkins-rhel9 | — | — |
| rhbk | keycloak-rhel9 | — | — |
| rhoai | odh-modelmesh-rhel9 | — | — |
CVSS provenance
nvdv4.06.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
vendor_redhat6.9MEDIUM
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Red Hat
org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
vendor_redhat·2026-10-03·CVSS 6.9
CVE-2026-71892 [MEDIUM] CWE-1024 org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-siz
GHSA
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a mess
ghsa_unreviewed·2026-10-03
CVE-2026-71892 [MEDIUM] CWE-697 In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a mess
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size
VulDB
Legion of the Bouncy Castle BC-JAVA/BC-FJA Key Size Validation JceKeyTransRecipient.java comparison
vuldb·2026-10-03·CVSS 6.9
CVE-2026-71892 [MEDIUM] Legion of the Bouncy Castle BC-JAVA/BC-FJA Key Size Validation JceKeyTransRecipient.java comparison
A vulnerability was found in Legion of the Bouncy Castle BC-JAVA and BC-FJA and classified as critical. This issue affects the function org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation of the file bouncycastle/cms/jcajce/JceKeyTransRecipient.java of the component Key Size Validation. The manipulation results in incorrect comparison.
This vulnerability is known as CVE-2026-71892. It is possible to launch the attack remotely. No exploit is available.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-71892 mariadb-java-client: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 mariadb-java-client: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
CVE-2026-71892 mariadb-java-client: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte arr
Bugzilla
CVE-2026-71892 apache-sshd: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 apache-sshd: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
CVE-2026-71892 apache-sshd: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array again
Bugzilla
CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array again
Bugzilla
CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
CVE-2026-71892 voms-api-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array aga
Bugzilla
CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against t
Bugzilla
CVE-2026-71892 fop: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 fop: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
CVE-2026-71892 fop: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the i
Bugzilla
CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
bugzilla·2026-10-13·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
CVE-2026-71892 canl-java: Bouncy Castle: Key-size validation bypass via improper algorithm check [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against
Bugzilla
CVE-2026-71892 org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
bugzilla·2026-10-03·CVSS 6.9
CVE-2026-71892 [MEDIUM] CVE-2026-71892 org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
CVE-2026-71892 org.bouncycastle/bcpkix-jdk18on: org.bouncycastle/bcpkix-fips: bouncycastle: Bouncy Castle: Key-size validation bypass via improper algorithm check
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell throu
2026-10-03
Published