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CVE.org (no NVD analysis yet)· CNA bcorg

CVE-2026-17508: Password-based KDF cost parameters honoured unbounded from untrusted input across the remaining PBE entry points

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.41% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • Fixed version: Legion of the Bouncy Castle Inc. BC-FJA 1.0.13, 2.0.13, 2.1.13; Legion of the Bouncy Castle Inc. BC-JAVA 1.86; Legion of the Bouncy Castle Inc. BC-LTS-JAVA 2.73.13.

Low priority for now. Upgrade to Legion of the Bouncy Castle Inc. BC-FJA 1.0.13, 2.0.13, 2.1.13; Legion of the Bouncy Castle Inc. BC-JAVA 1.86; Legion of the Bouncy Castle Inc. BC-LTS-JAVA 2.73.13 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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).

MediumCVSS 5.3 · v4.0—No exploit Fix available
Published
Oct 2, 2026
Updated
Oct 2, 2026
EPSS
0.4% · 36th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · bcorg
5.3
NVD has not scored this yet; the score shown is the CNA’s.

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/U:Amber

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-17508

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (bcorg). Independent of NVD's CPE analysis and usually ahead of it.

  • Legion of the Bouncy Castle Inc. BC-FJA

    • 1.0.0 and later · before 1.0.13affected · maven
    • 2.0.0 and later · before 2.0.13affected · maven
    • 2.1.0 and later · before 2.1.13affected · maven

  • Legion of the Bouncy Castle Inc. BC-JAVA

    • before 1.86affected · maven
    • before 1.86affected · maven

  • Legion of the Bouncy Castle Inc. BC-LTS-JAVA

    • 2.73.0 and later · before 2.73.13affected · maven
    • 2.73.0 and later · before 2.73.13affected · maven

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12bouncycastlefrom 0—
Debian:14bouncycastlebefore 1.86-11.86-1
openSUSE:Leap 16.0bouncycastlebefore 1.86-160000.1.11.86-160000.1.1
openSUSE:Tumbleweedbouncycastlebefore 1.86-1.11.86-1.1
SUSE:Linux Enterprise Module for Development Tools 15 SP7bouncycastlebefore 1.86-150200.3.41.11.86-150200.3.41.1

Same product

legion of the bouncy castle inc.: all records

Other highest-scoring records for the same primary product.

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    37Monitor
  • CVE-2026-71885MLS X.509 credential not bound to the LeafNode signature key
    36Monitor
  • CVE-2026-5598Non-constant time comparisons risk private key leakage in FrodoKEM.
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-3505Apr 15, 2026 · Unbounded PGP AEAD chunk size leads to pre-auth resource exhaustion.
    34Monitor
  • ← EarlierCVE-2026-5588Apr 15, 2026 · PKIX draft CompositeVerifier accepts empty signature sequence as valid.
    25Monitor
  • Later →CVE-2026-18036Oct 2, 2026 · NTRU leaks private key information by reducing secret values with a non-constant-time integer division
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Legion of the Bouncy Castle Inc. BC-FJA1.0.13Vendor (CNA)
Legion of the Bouncy Castle Inc. BC-FJA2.0.13Vendor (CNA)
Legion of the Bouncy Castle Inc. BC-FJA2.1.13Vendor (CNA)
Legion of the Bouncy Castle Inc. BC-JAVA1.86Vendor (CNA)
Legion of the Bouncy Castle Inc. BC-LTS-JAVA2.73.13Vendor (CNA)
debian:bouncycastle1.86-1 · Debian:14Package registry (OSV)
opensuse:bouncycastle1.86-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:bouncycastle1.86-150200.3.41.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 4, 2026+34 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-978731 days apartLegacy PBES1 and PKCS#12 PBE iteration count honoured unbounded in the raw JCA provider
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
P
Scope
X

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. SSVC exploitation— → none
  2. Exploit maturity— → none
  3. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records