CWE-780 RSA Without OAEP Padding

Description

RSA Without OAEP Padding

Reference: https://cwe.mitre.org/data/definitions/780.html

OWASP Category: A02:2021 – Cryptographic Failures

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Vulnerable Pattern

❌ Example 1: Vulnerable Pattern

// VULNERABLE: PKCS1 padding is susceptible to padding oracle attacks
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encrypted = cipher.doFinal(plaintext);

Why it's vulnerable: This pattern is vulnerable to RSA Without OAEP Padding

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Deterministic Fix

✅ Secure Implementation: Secure Implementation

// SECURE: Use OAEP padding
Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encrypted = cipher.doFinal(plaintext);

// Or with explicit OAEP parameters
OAEPParameterSpec oaepParams = new OAEPParameterSpec(
    "SHA-256",
    "MGF1",
    MGF1ParameterSpec.SHA256,
    PSource.PSpecified.DEFAULT
);
cipher.init(Cipher.ENCRYPT_MODE, publicKey, oaepParams);

Why it's secure: Implements proper protection against RSA Without OAEP Padding

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Detection Pattern

Look for these patterns in your codebase:

# Find RSA with weak padding
grep -rn "RSA.*PKCS1\|RSA/ECB/PKCS1" --include="*.java"

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Remediation Steps

1. Replace PKCS1Padding with OAEPWithSHA-256AndMGF1Padding

2. Use SHA-256 or stronger for OAEP hash

3. Consider using hybrid encryption (AES + RSA)

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Key Imports

import javax.crypto.Cipher;

import javax.crypto.spec.OAEPParameterSpec;

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Verification

After remediation:

• Run SAST scanner to confirm vulnerability is resolved

• Review all instances of the vulnerable pattern

• Add unit tests that verify the secure implementation

• Check for similar patterns in related code

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Trigger Examples

Fix CWE-780 vulnerability
Resolve RSA Without OAEP Padding issue
Secure this Java code against rsa without oaep padding
SAST reports CWE-780

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Common Vulnerable Locations

Layer	Files	Patterns

| Controller | *Controller.java | User input handling |

| Service | *Service.java | Business logic |

| Repository | *Repository.java | Data access |

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References

• CWE-780: RSA Without OAEP

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Source: Generated by Java CWE Security Skills Generator Last Updated: 2026-03-07