# CVE-2020-26939: Observable Differences in Behavior to Error Inputs in Bouncy Castle > Attackers can leak private RSA key information via timing differences in OAEP decoding errors in the Bouncy Castle library. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 2 Nov 2020 - **Updated:** 4 Aug 2024 - **Also known as:** DEBIAN-CVE-2020-26939, DLA-2433-1, GHSA-72m5-fvvv-55m6, UBUNTU-CVE-2020-26939 ## What is CVE-2020-26939? CVE-2020-26939 is a medium-severity vulnerability in n/a, published on 2 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. Weakness: CWE-203 (Observable Discrepancy) ## Which versions are affected by CVE-2020-26939? 16 open source packages ship an affected version, including org.bouncycastle:bc-fips, org.bouncycastle:bcprov-ext-jdk15on and org.bouncycastle:bcprov-ext-jdk16. It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.bouncycastle:bc-fips` | Maven | All versions | 1.0.2 | | `org.bouncycastle:bc-fips` | Maven | All versions | 1.0.2 | | `org.bouncycastle:bcprov-ext-jdk15on` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-ext-jdk15on` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-ext-jdk16` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-ext-jdk16` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk14` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk14` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15on` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15on` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15to18` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk15to18` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk16` | Maven | All versions | 1.61 | | `org.bouncycastle:bcprov-jdk16` | Maven | All versions | 1.61 | Products: Bouncycastle Fips Java Api, Bouncycastle Legion-of-the-Bouncy-Castle. ## How do I fix CVE-2020-26939? Upgrade org.bouncycastle:bc-fips to 1.0.2 or later. ## Is CVE-2020-26939 being exploited? There is no known exploitation of CVE-2020-26939 in the wild and no public exploit code. ## Other vulnerabilities in n/a - [CVE-2022-45146](https://insights.sbomify.com/CVE-2022-45146/): Garbage collection issue in BC-FJA in Java 13 and later (medium 5.5) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-26939 and fix it if it is affected. What it is: CVE-2020-26939 is a medium-severity vulnerability in n/a, published on 2 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2020-26939 in the wild and no public exploit code. Affected packages and fixed versions: - org.bouncycastle:bc-fips (Maven): affected all versions; fixed in 1.0.2 - org.bouncycastle:bc-fips (Maven): affected all versions; fixed in 1.0.2 - org.bouncycastle:bcprov-ext-jdk15on (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-ext-jdk15on (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-ext-jdk16 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-ext-jdk16 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk14 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk14 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk15 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk15 (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk15on (Maven): affected all versions; fixed in 1.61 - org.bouncycastle:bcprov-jdk15on (Maven): affected all versions; fixed in 1.61 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-26939/ (Markdown: https://insights.sbomify.com/CVE-2020-26939/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26939 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26939 - OSV: https://osv.dev/vulnerability/CVE-2020-26939 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-26939/ Summaries are generated and may contain mistakes; the official description above is the record.