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MEDIUM severity

Observable Differences in Behavior to Error Inputs in Bouncy CastleGHSA-72m5-fvvv-55m6

MEDIUMFix: bcgit/bc-java@930f8b2

GHSA-72m5-fvvv-55m6 is a medium-severity (CVSS 5.3) CWE-203 vulnerability in org.bouncycastle:bcprov-jdk14. A fix is available for org.bouncycastle:bcprov-jdk14 — see the affected versions and patch details below.

Also known asCVE-2020-26939
Published
Updated
Affected
8 pkgs
Patched
8 / 8
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk
0.41%1.25%2.09%2.94%2.4%0.9%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

8 pkgs affected
☕org.bouncycastle:bcprov-jdk14☕org.bouncycastle:bcprov-jdk15☕org.bouncycastle:bcprov-jdk16☕org.bouncycastle:bc-fips☕org.bouncycastle:bcprov-ext-jdk15on☕org.bouncycastle:bcprov-ext-jdk16☕org.bouncycastle:bcprov-jdk15on☕org.bouncycastle:bcprov-jdk15to18

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

In Legion of the Bouncy Castle BC before 1.61 and BC-FJA before 1.0.1.2, attackers can obtain sensitive information about a private exponent because of Observable Differences in Behavior to Error Inputs. This occurs in org.bouncycastle.crypto.encodings.OAEPEncoding. Sending invalid ciphertext that decrypts to a short payload in the OAEP Decoder could result in the throwing of an early exception, potentially leaking some information about the private exponent of the RSA private key performing the encryption.

Affected Packages

8 total 8 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.bouncycastle:bcprov-jdk14all versions1.61org.bouncycastle:bcprov-jdk14:1.61
☕Mavenorg.bouncycastle:bcprov-jdk15all versions1.61org.bouncycastle:bcprov-jdk15:1.61
☕Mavenorg.bouncycastle:bcprov-jdk16all versions1.61org.bouncycastle:bcprov-jdk16:1.61
☕Mavenorg.bouncycastle:bc-fipsall versions1.0.2org.bouncycastle:bc-fips:1.0.2
☕Mavenorg.bouncycastle:bcprov-ext-jdk15onall versions1.61org.bouncycastle:bcprov-ext-jdk15on:1.61
☕Mavenorg.bouncycastle:bcprov-ext-jdk16all versions1.61org.bouncycastle:bcprov-ext-jdk16:1.61

Affected Products

2 products · 2 configurations
Application
fips java apibouncycastle
< 1.0.1.2
range
Application
legion-of-the-bouncy-castlebouncycastle
< 1.61
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.bouncycastle:bcprov-jdk14, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.bouncycastle:bcprov-jdk14 to 1.61 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-72m5-fvvv-55m6 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

In Legion of the Bouncy Castle BC before 1.55 and BC-FJA before 1.0.2, attackers can obtain sensitive information about a private exponent because of Observable Differences in Behavior to Error Inputs. This occurs in org.bouncycastle.crypto.encodings.OAEPEncoding. Sending invalid ciphertext that decrypts to a short payload in the OAEP Decoder could result in the throwing of an early exception, potentially leaking some information about the private exponent of the RSA private key performing the encryption.
O3 Security · Impact-Aware SCA

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