CVE-2026-32614: SM9 Infinity-Point Ciphertext Forgery Vulnerability

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.2%, percentile 14: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 14% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes github.com/emmansun/gmsm (Go) < 0.41.1, fixed in 0.41.1. Check your lockfile, including transitive dependencies.

What it is

Go ShangMi (Commercial Cryptography) Library (GMSM) is a cryptographic library that covers the Chinese commercial cryptographic public algorithms SM2/SM3/SM4/SM9/ZUC. Prior to 0.41.1, the current SM9 decryption implementation contains an infinity-point ciphertext forgery vulnerability. The root cause is that, during decryption, the elliptic-curve point C1 in the ciphertext is only deserialized and checked to be on the curve, but the implementation does not explicitly reject the point at infinity. In the current implementation, an attacker can construct C1 as the point at infinity, causing the bilinear pairing result to degenerate into the identity element in the GT group. As a result, a critical part of the key derivation input becomes a predictable constant. An attacker who only knows the target user's UID can derive the decryption key material and then forge a ciphertext that passes the integrity check. This vulnerability is fixed in 0.41.1.

From the GitHub advisory

Overview

The current SM9 decryption implementation contains an infinity-point ciphertext forgery vulnerability. The root cause is that, during decryption, the elliptic-curve point C1 in the ciphertext is only deserialized and checked to be on the curve, but the implementation does not explicitly reject the point at infinity.

In the current implementation, an attacker can construct C1 as the point at infinity, causing the bilinear pairing result to degenerate into the identity element in the GT group. As a result, a critical part of the key derivation input becomes a predictable constant. An attacker who only knows the target user's UID can derive the decryption key material and then forge a ciphertext that passes the integrity check.

Impact

The direct impact of this vulnerability is ciphertext forgery, not confidentiality loss.

Weakness type: CWE-347, CWE-20.

Product: github.com/emmansun/gmsm (Go) · Assigned by: GitHub_M · Published: 2026-03-13

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.24% probability of exploitation activity in the next 30 days; percentile 14.

Timeline

• 2026-03-13 — CVE record published by GitHub_M
• 2026-03-13 — GitHub-reviewed advisory GHSA-5xxp-2vrj-x855 published (critical)
• 2026-03-16 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-5xxp-2vrj-x855 github.com
2. CVE.org record CVE-2026-32614 cve.org
3. NVD entry CVE-2026-32614 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. pkg.go.dev pkg.go.dev

Critical Go advisories · Today’s Security Digest