CVE-2026-75805 (GCVE-0-2026-75805)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-11-10 12:49
VLAI
Title
NULL Pointer Dereference in CMP Client Revocation Response Handling
Summary
Issue summary: A CMP client that requests certificate revocation on the basis of a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when processing a crafted revocation response. Impact summary: The NULL pointer dereference happens on a read which leads to a crash and a Denial of Service for the affected client application. CWE: CWE-476: NULL-pointer dereference Description: A CMP client revoking a certificate has to tell the server which certificate to revoke, and may do so by supplying a PKCS#10 CSR instead of the certificate itself or its issuer name and serial number. This is 'openssl cmp -cmd rr -csr <file>' on the command line, or OSSL_CMP_exec_RR_ses() with the certificate supplied via OSSL_CMP_CTX_set1_p10CSR() through the API. A CSR does not contain the issuer name and serial number of the certificate, so the client does not send them. A server may optionally name the certificate it revoked in its response, and the client then compares that name against what it sent. Having sent neither an issuer name nor a serial number, it has nothing to compare against, and a server returning a specially crafted name causes the client to read from a NULL pointer and crash. The revocation response is checked for valid message protection before the affected code is reached, so an attacker must be a malicious or compromised CMP server, or a man-in-the-middle in possession of the secret used for message protection. Clients that identify the certificate to be revoked by a certificate or by issuer and serial number rather than by a PKCS#10 CSR are not affected. FIPS impact: no No FIPS modules are affected by this issue, as the CMP protocol implementation is outside the OpenSSL FIPS module boundary.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-29 16:54 UTC
CWE
  • CWE-476 - NULL-pointer dereference
Assigner
openssl CNA under the mitre root
CNA scorecard B 78/100 over 48 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
OpenSSL OpenSSL Affected: 4.0.0 , < 4.0.3 (semver)
Affected: 3.6.0 , < 3.6.5 (semver)
Affected: 3.5.0 , < 3.5.9 (semver)
Affected: 3.4.0 , < 3.4.8 (semver)
Affected: 3.0.0 , < 3.0.23 (semver)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Affected: V3.1.7 , < * (custom)
guessed Create a notification for this product.
Date Public
2026-09-29 14:21
Credits
Bhabani Sankar Das Bhabani Sankar Das Norbert Pocs
Show details on NVD website
To clipboard 

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                "version": "2.0.3"
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            "tags": [
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            "tags": [
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          }
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        "sourceIdentifier": "openssl-security@openssl.org",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
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                "lang": "en",
                "value": "CWE-476"
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            ],
            "source": "openssl-security@openssl.org",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-12T03:04:09+00:00",
      "cve": "CVE-2026-75805",
      "id": "CVE-2026-75805",
      "initial_release_date": "2026-09-29T15:32:20.408000+00:00",
      "product_status:fixed": "112",
      "product_status:known_affected": "15",
      "product_status:known_not_affected": "73",
      "product_status:under_investigation": "17",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "openssl: openssl: Denial of Service via crafted CMP certificate revocation response",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-75805.json",
      "version": "3"
    },
    "vulnrichment": {
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                "vendor": "Siemens",
                "versions": [
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                    "status": "affected",
                    "version": "V3.1.7",
                    "versionType": "custom"
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                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)",
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                "versions": [
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                    "lessThan": "*",
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                    "version": "V3.1.7",
                    "versionType": "custom"
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                ]
              },
              {
                "defaultStatus": "unknown",
                "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "*",
                    "status": "affected",
                    "version": "V3.1.7",
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                  }
                ]
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-11-10T12:49:43.797Z",
              "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
              "shortName": "siemens-SADP"
            },
            "references": [
              {
                "url": "https://cert-portal.siemens.com/productcert/html/ssa-457936.html"
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            ],
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          },
          {
            "metrics": [
              {
                "cvssV3_1": {
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                  "attackVector": "NETWORK",
                  "availabilityImpact": "LOW",
                  "baseScore": 5.3,
                  "baseSeverity": "MEDIUM",
                  "confidentialityImpact": "NONE",
                  "integrityImpact": "NONE",
                  "privilegesRequired": "NONE",
                  "scope": "UNCHANGED",
                  "userInteraction": "NONE",
                  "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
                  "version": "3.1"
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              },
              {
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                    "role": "CISA Coordinator",
                    "timestamp": "2026-09-29T16:54:03.315064Z",
                    "version": "2.0.3"
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                  "type": "ssvc"
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              "dateUpdated": "2026-09-29T16:54:26.744Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "OpenSSL",
              "vendor": "OpenSSL",
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                  "status": "affected",
                  "version": "4.0.0",
                  "versionType": "semver"
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              "type": "reporter",
              "value": "Bhabani Sankar Das"
            },
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              "type": "remediation developer",
              "value": "Bhabani Sankar Das"
            },
            {
              "lang": "en",
              "type": "remediation developer",
              "value": "Norbert Pocs"
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          ],
          "datePublic": "2026-09-29T14:21:57.000Z",
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              "supportingMedia": [
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                  "type": "text/html",
                  "value": "Issue summary: A CMP client that requests certificate revocation on the basis\u003cbr\u003eof a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when\u003cbr\u003eprocessing a crafted revocation response. \u003cbr\u003e\u003cbr\u003eImpact summary: The NULL pointer dereference happens on a read which \u003cbr\u003eleads to a crash and a Denial of Service for the affected client application.\u003cbr\u003e\u003cbr\u003eCWE: CWE-476: NULL-pointer dereference\u003cbr\u003e\u003cbr\u003eDescription: A CMP client revoking a certificate has to tell the server which\u003cbr\u003ecertificate to revoke, and may do so by supplying a PKCS#10 CSR instead of the\u003cbr\u003ecertificate itself or its issuer name and serial number. This is\u003cbr\u003e\u0027openssl cmp -cmd rr -csr \u003cfile\u003e\u0027 on the command line, or\u003cbr\u003eOSSL_CMP_exec_RR_ses() with the certificate supplied via\u003cbr\u003eOSSL_CMP_CTX_set1_p10CSR() through the API.\u003cbr\u003e\u003cbr\u003eA CSR does not contain the issuer name and serial number of the certificate,\u003cbr\u003eso the client does not send them. A server may optionally name the\u003cbr\u003ecertificate it revoked in its response, and the client then compares that\u003cbr\u003ename against what it sent. Having sent neither an issuer name nor a serial\u003cbr\u003enumber, it has nothing to compare against, and a server returning a specially\u003cbr\u003ecrafted name causes the client to read from a NULL pointer and crash.\u003cbr\u003e\u003cbr\u003eThe revocation response is checked for valid message protection before\u003cbr\u003ethe affected code is reached, so an attacker must be a malicious or\u003cbr\u003ecompromised CMP server, or a man-in-the-middle in possession of the\u003cbr\u003esecret used for message protection. Clients that identify the certificate\u003cbr\u003eto be revoked by a certificate or by issuer and serial number rather\u003cbr\u003ethan by a PKCS#10 CSR are not affected.\u003cbr\u003e\u003cbr\u003eFIPS impact: no\u003cbr\u003eNo FIPS modules are affected by this issue, as the CMP protocol\u003cbr\u003eimplementation is outside the OpenSSL FIPS module boundary."
                }
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        "datePublished": "2026-09-29T15:32:20.408Z",
        "dateReserved": "2026-08-18T09:34:32.659Z",
        "dateUpdated": "2026-11-10T12:49:43.797Z",
        "state": "PUBLISHED"
      },
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    }
  }
}



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