2.7

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-21895

CVE-2026-21895: rsa crate has potential panic on a prime being equal to 1

The rsa crate is an RSA implementation written in rust. Prior to version 0.9.10, when creating a RSA private key from its components, the construction panics instead of returning an error when one of the primes is 1. Version 0.9.10 fixes the issue.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-21895

CVE-2026-21895:

2.7

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
rsa	rust	<= 0.9.9	0.9.10

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the rsa crate's handling of private key components. Specifically, when creating a private key, the code did not correctly handle the case where one of the provided primes is equal to 1. The analysis of the patch commit 2926c91bef7cb14a7ccd42220a698cf4b1b692f7 reveals the exact location of the flaw. The file src/key.rs contains the RsaPrivateKey::precompute function, which is responsible for validating the prime numbers. The original code only checked if a prime was less than 1 (*prime < BigUint::one()), which incorrectly allowed a prime of 1 to be considered valid. This would lead to a panic (division by zero) later in the key generation process. The patch corrects this by changing the condition to *prime <= BigUint::one(), ensuring that primes of 1 are properly rejected. The functions RsaPrivateKey::from_components and RsaPrivateKey::from_multi_prime_components are the public-facing functions that call the vulnerable precompute function, making them the entry points for exploiting this vulnerability. Therefore, any of these three functions could appear in a stack trace during an exploit.

Vulnerable functions

RsaPrivateKey::precompute

src/key.rs

This function performs precomputation for the private key. The vulnerability lies in the check for prime validity. The original code checked `*prime < BigUint::one()`, which allowed a prime of 1 to pass, leading to a panic later in the code. The patch changes this to `*prime <= BigUint::one()`, correctly identifying 1 as an invalid prime.

RsaPrivateKey::from_components

src/key.rs

This function is an entry point for creating an `RsaPrivateKey`. It calls the vulnerable `precompute` function. Providing a prime of 1 to this function would trigger the panic in `precompute` in the vulnerable versions.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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