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NVD / CVE Program· CNA mitre

CVE-2020-26939: 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…

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: 0.92% (FIRST EPSS); higher than 60.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: bouncycastle (Debian:12) 1.61-1; bouncycastle (Debian:9) 1.56-1+deb9u3; org.bouncycastle:bc-fips (Maven) 1.0.2.
  • Mentioned 3 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to bouncycastle (Debian:12) 1.61-1; bouncycastle (Debian:9) 1.56-1+deb9u3; org.bouncycastle:bc-fips (Maven) 1.0.2 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 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.

MediumCVSS 5.3 · v3.1—No exploit Fix available
Published
Nov 2, 2020
Updated
Jun 16, 2026
EPSS
0.9% · 60th 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 · 0.9%

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

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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.

VendorProduct
bouncycastlefips java api
bouncycastlelegion-of-the-bouncy-castle

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • bouncycastle fips java apibefore 1.0.1.2
  • bouncycastle legion-of-the-bouncy-castlebefore 1.61

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12bouncycastlebefore 1.61-11.61-1
Debian:9bouncycastlebefore 1.56-1+deb9u31.56-1+deb9u3
Mavenorg.bouncycastle:bc-fipsbefore 1.0.21.0.2
Mavenorg.bouncycastle:bcprov-ext-jdk15onbefore 1.611.61
Mavenorg.bouncycastle:bcprov-ext-jdk16before 1.611.61
Mavenorg.bouncycastle:bcprov-jdk14before 1.611.61
Mavenorg.bouncycastle:bcprov-jdk15before 1.611.61
Mavenorg.bouncycastle:bcprov-jdk15onbefore 1.611.61
Mavenorg.bouncycastle:bcprov-jdk15to18before 1.611.61
Mavenorg.bouncycastle:bcprov-jdk16before 1.611.61

Same product

bouncycastle: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-45146An issue was discovered in the FIPS Java API of Bouncy Castle BC-FJA before 1.0.2.4.
    22Monitor

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
debian:bouncycastle1.61-1 · Debian:12Package registry (OSV)
Maven:org.bouncycastle:bc-fips1.0.2Package registry (OSV)
Maven:org.bouncycastle:bcprov-ext-jdk15on1.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-ext-jdk161.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-jdk141.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-jdk151.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-jdk15on1.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-jdk15to181.61Package registry (OSV)
Maven:org.bouncycastle:bcprov-jdk161.61Package 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.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

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

No commit or PR link among the references.

Credits

All researchers

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

No credits in the CNA record.

Variant candidates

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

No nightly-computed relations.

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

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

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-203 · Observable Discrepancy

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

nvd-primary

Attack context

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

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (1 more)

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

All records