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OpenAdvisories
Medium · 5.3 CVE-2026-17508 EUVD-2026-91236GHSA-m3x3-p27c-whhp

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

Published Oct 2, 2026 · Updated Oct 2, 2026 · Assigned by bcorg

Description

In 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).

Affected products

VendorProductAffectedFixed
Legion of the Bouncy Castle BC-JAVA < 1.86 1.86
Legion of the Bouncy Castle BC-LTS-JAVA 2.73.0 – < 2.73.13 2.73.13
Legion of the Bouncy Castle BC-FJA 1.0.0 – < 1.0.13, 2.0.0 – < 2.0.13, 2.1.0 – < 2.1.13 1.0.13

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 bouncycastle 1.86-1 —
Debian 13 bouncycastle No fix yet —
Debian 12 bouncycastle No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 bouncycastle No fix yet —
Ubuntu 26.04 LTS bouncycastle No fix yet —
Show 5 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 24.04 LTS bouncycastle No fix yet —
Ubuntu Pro 22.04 LTS bouncycastle No fix yet —
Ubuntu Pro 20.04 LTS bouncycastle No fix yet —
Ubuntu Pro 18.04 LTS bouncycastle No fix yet —
Ubuntu Pro 16.04 LTS bouncycastle No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES 15 SP6 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES 15 SP5 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES 15 SP4 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 bouncycastle 1.86-160000.1.1 SUSE-SU-2026:24461-1
SLES for SAP 15 SP6 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES for SAP 15 SP5 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES for SAP 15 SP4 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLES 16.0 bouncycastle 1.86-160000.1.1 SUSE-SU-2026:24461-1
SLE HPC 15 SP5 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
SLE HPC 15 SP4 bouncycastle 1.86-150200.3.41.1 SUSE-SU-2026:4797-1
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed bouncycastle 1.86-1.1 openSUSE-SU-2026:12090-1
openSUSE Leap 16.0 bouncycastle 1.86-160000.1.1 openSUSE-SU-2026:22169-1

Advisories 5

References