Password-based KDF cost parameters honoured unbounded from untrusted input across the remaining PBE entry points

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-17508
StatePUBLISHED
Assignerbcorg
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-02 08:17:01 UTC
Updated2026-10-02 18:17:03 UTC
DescriptionIn Bouncy Castle for Java before 1.86, several password-based key derivation entry points ran the KDF with cost parameters taken from the untrusted input being processed, without bounding them, so a small input could dictate an arbitrary amount of work before any password or integrity check could reject it. The affected paths are the RFC 9579 PBMAC1 MAC calculator builders, which took the PBKDF2 iteration count and derived-key length straight out of PBMAC1Params (JcePBMac1CalculatorBuilder, and PKCS12PBEUtils.createPBMac1Calculator reached from PKCS12PfxPdu.isMacValid); the scrypt parallelization parameter p in the PKCS#8 and PKCS#12 cost guards, which bounded only the cost parameter N and the block size r even though the scratch buffer scales with r times p, so the configured memory ceiling could be evaded entirely; the raw JCA PBKDF2 provider (org.bouncycastle.jcajce.provider.symmetric.PBEPBKDF2); and the bcrypt round count read from an encrypted OpenSSH v1 private key's own kdfoptions. Each now bounds the parameter before deriving, in line with the caps already applied elsewhere in the tree, with the OpenSSH round count configurable through the new org.bouncycastle.openssh.max_rounds property. This completes the bounding begun in 1.85 for the PKCS#8 / PBES2 decryptors (CVE-2026-15055). This issue also affects Bouncy Castle for Java LTS before 2.73.13, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Risk And Classification

Primary CVSS: v4.0 5.3 MEDIUM from 91579145-5d7b-4cc5-b925-a0262ff19630

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/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

EPSS: 0.004360000 probability, percentile 0.356040000 (date 2026-10-02)

Problem Types: CWE-770 | CWE-770 CWE-770 Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
4.091579145-5d7b-4cc5-b925-a0262ff19630Secondary5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/U:Amber

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
None
Integrity
None
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/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 Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Legion Of The Bouncy Castle Inc. BC-JAVA affected 1.86 maven all
CNA Legion Of The Bouncy Castle Inc. BC-JAVA affected 1.86 maven all
CNA Legion Of The Bouncy Castle Inc. BC-LTS-JAVA affected 2.73.0 2.73.13 maven all
CNA Legion Of The Bouncy Castle Inc. BC-LTS-JAVA affected 2.73.0 2.73.13 maven all
CNA Legion Of The Bouncy Castle Inc. BC-FJA affected 1.0.0 1.0.13 maven all
CNA Legion Of The Bouncy Castle Inc. BC-FJA affected 2.0.0 2.0.13 maven all
CNA Legion Of The Bouncy Castle Inc. BC-FJA affected 2.1.0 2.1.13 maven all

References

ReferenceSourceLinkTags
github.com/bcgit/bc-java/commit/882fdab53f6c4c150a5d6a4e6ef1fc05d382385a 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/commit/442393bf187c914b1e66fbed4fab532a1fe06c6a 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/commit/20ed9e203caec91d25cd386ceb6d364e9b068f67 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9017508 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/commit/e72bc0681ff4227fced912ef7394daf7b7d57bb3 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/commit/480d878aa6f7dc8b20403064f304bbe0decbbb1a 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
github.com/bcgit/bc-java/commit/766a31026ac24ed3c6cad8662058ba450c338da1 91579145-5d7b-4cc5-b925-a0262ff19630 github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Mirko Swillus on behalf of Alpha-Omega (alpha-omega.dev), using Scrutineer with an Anthropic Claude model provided through Project Glasswing (en)

CNA: Yu Bao from the PayPal Cyber Security Team (en)

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