CVE-2020-26939
Observable Differences in Behavior to Error Inputs in Bouncy Castle
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
5.3
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.
- Record
CVE-2020-26939- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2020-26939- Updated
- 2026-11-02
EUVDEUVD-2021-0779 No score
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.
- Record
EUVD-2021-0779- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-72m5-fvvv-55m6
5.3
Observable Differences in Behavior to Error Inputs in Bouncy Castle
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.
- Record
GHSA-72m5-fvvv-55m6- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
OSV
5.3
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.
- Record
CVE-2020-26939- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVDEBIAN-CVE-2020-26939
5.3
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.
- Record
DEBIAN-CVE-2020-26939- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-72m5-fvvv-55m6
5.3
Observable Differences in Behavior to Error Inputs in Bouncy Castle
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.
- Record
GHSA-72m5-fvvv-55m6- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2020-26939
5.3
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.
- Record
UBUNTU-CVE-2020-26939- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.bouncycastle:bcprov-jdk14Maven |
before 1.61 | 1.61 |
org.bouncycastle:bcprov-jdk15Maven |
before 1.61 | 1.61 |
org.bouncycastle:bcprov-jdk16Maven |
before 1.61 | 1.61 |
org.bouncycastle:bc-fipsMaven |
before 1.0.2 | 1.0.2 |
org.bouncycastle:bcprov-ext-jdk15onMaven |
before 1.61 | 1.61 |
org.bouncycastle:bcprov-ext-jdk16Maven |
before 1.61 | 1.61 |
org.bouncycastle:bcprov-jdk15onMaven |
before 1.61 | 1.61 |
org.bouncycastle:bcprov-jdk15to18Maven |
before 1.61 | 1.61 |
bouncycastleDebian:12 |
before 1.61-1 | 1.61-1 |
bouncycastleDebian:13 |
before 1.61-1 | 1.61-1 |
Show 11 moreShow less
| Package | Affected | Fixed |
|---|---|---|
bouncycastleDebian:14 |
before 1.61-1 | 1.61-1 |
bouncycastleDebian:9 |
before 1.56-1+deb9u3, plus listed versions 1.56-11.56-1+deb9u11.56-1+deb9u2 |
1.56-1+deb9u3 |
org.bouncycastle:bcprov-jdk14Maven |
before 1.61, plus listed versions 1.381.431.441.451.46 Show 13 moreShow less1.471.481.491.501.511.531.541.551.561.571.581.591.60 |
1.61 |
org.bouncycastle:bcprov-jdk15Maven |
before 1.61, plus listed versions 1.321.381.401.431.441.451.46 |
1.61 |
org.bouncycastle:bcprov-jdk16Maven |
before 1.61, plus listed versions 1.381.401.431.441.451.46 |
1.61 |
org.bouncycastle:bc-fipsMaven |
before 1.0.2, plus listed versions 1.0.01.0.1 |
1.0.2 |
org.bouncycastle:bcprov-ext-jdk15onMaven |
before 1.61, plus listed versions 1.461.471.481.491.50 Show 10 moreShow less1.511.521.531.541.551.561.571.581.591.60 |
1.61 |
org.bouncycastle:bcprov-ext-jdk16Maven |
before 1.61, plus listed versions 1.451.46 |
1.61 |
org.bouncycastle:bcprov-jdk15onMaven |
before 1.61, plus listed versions 1.461.471.481.491.50 Show 10 moreShow less1.511.521.531.541.551.561.571.581.591.60 |
1.61 |
bouncycastleUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.49+dfsg-3ubuntu11.51-4ubuntu11.51-4ubuntu1+esm1 |
None known |
bouncycastleUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.57-11.58-11.59-11.59-1ubuntu0.1~esm1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-26939 is a medium vulnerability (CVSS 5.3) in Bouncycastle Fips Java Api, published November 2, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.92%, the 60th percentile. Fixed in org.bouncycastle:bcprov-jdk14 1.61.
References
github.com/bcgit/bc-java/wiki/CVE-2020-26939
lists.apache.org/thread.html/r8c36ba34e80e05eecb1f80071cc834d705616f315b634ec0c7d8f42e%40%3Cissues.solr.apache.org%3E
nvd.nist.gov/vuln/detail/CVE-2020-26939
github.com/bcgit/bc-java/commit/930f8b274c4f1f3a46e68b5441f1e7fadb57e8c1
lists.debian.org/debian-lts-announce/2020/11/msg00007.html
lists.apache.org/thread.html/r8c36ba34e80e05eecb1f80071cc834d705616f315b634ec0c7d8f42e@%3Cissues.solr.apache.org%3E