7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-22700

CVE-2026-22700: RustCrypto Has Insufficient Length Validation in decrypt() in SM2-PKE

RustCrypto: Elliptic Curves is general purpose Elliptic Curve Cryptography (ECC) support, including types and traits for representing various elliptic curve forms, scalars, points, and public/secret keys composed thereof. In versions 0.14.0-pre.0 and 0.14.0-rc.0, a denial-of-service vulnerability exists in the SM2 public-key encryption (PKE) implementation: the decrypt() path performs unchecked slice::split_at operations on input buffers derived from untrusted ciphertext. An attacker can submit short/undersized ciphertext or carefully-crafted DER-encoded structures to trigger bounds-check panics (Rust unwinding) which crash the calling thread or process. This issue has been patched via commit e60e991.

(GitHub Advisory)

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CVE-2026-22700

CVE-2026-22700:

7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
sm2	rust	>= 0.14.0-pre.0, <= 0.14.0-rc.4

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability exists in the sm2 crate's public-key encryption implementation. The core issue lies in the internal decrypt function located in sm2/src/pke/decrypting.rs. This function uses slice::split_at to parse the provided ciphertext without first validating its length. As confirmed by the patch, the vulnerable code let (c1, c) = cipher.split_at(c1_len as usize); was replaced with a safe alternative ciphertext.split_at_checked(c1_len as usize).ok_or(Error)?;. If an attacker provides a ciphertext that is shorter than the expected length, the split_at call will panic, causing the thread to unwind and potentially crashing the entire application, resulting in a denial of service. The vulnerability is exposed through several public methods of the DecryptingKey struct, namely decrypt, decrypt_der, and decrypt_digest, which all act as entry points and pass untrusted input to the vulnerable internal decrypt function. The provided proofs-of-concept demonstrate how to trigger the panic by calling DecryptingKey::decrypt with a short buffer and DecryptingKey::decrypt_der with a crafted ASN.1 structure.

Vulnerable functions

decrypt

sm2/src/pke/decrypting.rs

The internal `decrypt` function used `slice::split_at` on the input `cipher` without prior length validation. A ciphertext shorter than the expected length would cause a panic, leading to a denial of service. The patch replaces the unsafe `split_at` with `split_at_checked` which returns an error instead of panicking.

DecryptingKey::decrypt

sm2/src/pke/decrypting.rs

This public method is an entry point for the decryption process. It takes raw ciphertext from a user and passes it to the internal `decrypt` function. A malicious, short ciphertext will trigger a panic in the downstream call, causing a denial of service.

DecryptingKey::decrypt_der

sm2/src/pke/decrypting.rs

This public method decrypts an ASN.1 DER-encoded ciphertext. It parses the input and passes components to the internal `decrypt` function. The vulnerability can be triggered by providing a DER-encoded structure with valid coordinates but short digest and cipher fields, which causes the downstream `decrypt` call to panic.

DecryptingKey::decrypt_digest

sm2/src/pke/decrypting.rs

This public method is an entry point for decryption that calls the vulnerable internal `decrypt` function, making it susceptible to the same denial-of-service panic when processing untrusted ciphertext.

Vulnerability Intelligence
Miggo AI

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WAF Rule

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Reasoning

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