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Observable Differences in Behavior to Error Inputs in Bouncy Castle

Moderate severity GitHub Reviewed Published Apr 22, 2021 to the GitHub Advisory Database • Updated Jul 17, 2025

Package

maven org.bouncycastle:bc-fips (Maven)

Affected versions

< 1.0.2

Patched versions

1.0.2
maven org.bouncycastle:bcprov-ext-jdk15on (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-ext-jdk16 (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-jdk14 (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-jdk15 (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-jdk15on (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-jdk15to18 (Maven)
< 1.61
1.61
maven org.bouncycastle:bcprov-jdk16 (Maven)
< 1.61
1.61

Description

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.

References

Published by the National Vulnerability Database Nov 2, 2020
Reviewed Apr 20, 2021
Published to the GitHub Advisory Database Apr 22, 2021
Last updated Jul 17, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

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

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(72nd percentile)

Weaknesses

Observable Discrepancy

The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not. Learn more on MITRE.

CVE ID

CVE-2020-26939

GHSA ID

GHSA-72m5-fvvv-55m6

Source code

No known source code

Credits

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