GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-5450 (GCVE-0-2026-5450)

Vulnerability from cvelistv5 – Published: 2026-04-20 20:55 – Updated: 2026-07-14 12:45
VLAI
Title
scanf %mc off-by-one heap buffer overflow
Summary
Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-21 16:11 UTC
CWE
  • CWE-122 - Heap-based buffer overflow
Assigner
References
Impacted products
Vendor Product Version CPE status
The GNU C Library glibc Affected: 2.7 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < V3.1.6 (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.5 , < V3.1.6 (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < V3.1.6 (custom)
guessed Create a notification for this product.
Date Public
2026-03-19 17:36
Credits
Rocket Ma
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 9.8,
              "baseSeverity": "CRITICAL",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-5450",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-21T16:11:50.875542Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-21T19:49:53.221Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V3.1.6",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V3.1.6",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V3.1.6",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V3.1.6",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "V3.1.6",
                "status": "affected",
                "version": "V3.1.5",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-14T12:45:30.709Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "glibc",
          "vendor": "The GNU C Library",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "2.7",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Rocket Ma"
        }
      ],
      "datePublic": "2026-03-19T17:36:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Calling the scanf family of functions with a %mc (malloc\u0027d character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow."
            }
          ],
          "value": "Calling the scanf family of functions with a %mc (malloc\u0027d character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-100",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-100 Overflow Buffers"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-122",
              "description": "CWE-122 Heap-based buffer overflow",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-20T20:55:41.170Z",
        "orgId": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
        "shortName": "glibc"
      },
      "references": [
        {
          "tags": [
            "issue-tracking"
          ],
          "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450"
        },
        {
          "tags": [
            "mailing-list"
          ],
          "url": "https://inbox.sourceware.org/libc-announce/b11f0003-6ec1-4bd6-b9de-9e38a4efeca3@redhat.com/T/#u"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "scanf %mc off-by-one heap buffer overflow",
      "x_generator": {
        "engine": "Vulnogram 1.0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
    "assignerShortName": "glibc",
    "cveId": "CVE-2026-5450",
    "datePublished": "2026-04-20T20:55:41.170Z",
    "dateReserved": "2026-04-02T21:47:21.403Z",
    "dateUpdated": "2026-07-14T12:45:30.709Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-5450",
      "date": "2026-09-16",
      "epss": "0.00502",
      "percentile": "0.4175"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-09T14:47:54.000Z",
      "cve": "CVE-2026-5450",
      "id": "msrc_CVE-2026-5450",
      "initial_release_date": "2026-04-22T01:01:30.000Z",
      "product_status:known_affected": "6",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "scanf %mc off-by-one heap buffer overflow",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-5450.json",
      "version": "7"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-5450\",\"sourceIdentifier\":\"3ff69d7a-14f2-4f67-a097-88dee7810d18\",\"published\":\"2026-04-20T21:16:36.850\",\"lastModified\":\"2026-07-14T13:19:01.520\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Calling the scanf family of functions with a %mc (malloc\u0027d character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.\"}],\"affected\":[{\"source\":\"3ff69d7a-14f2-4f67-a097-88dee7810d18\",\"affectedData\":[{\"vendor\":\"The GNU C Library\",\"product\":\"glibc\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"2.7\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]},{\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\",\"affectedData\":[{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"V3.1.6\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"V3.1.6\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"V3.1.6\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"V3.1.6\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"V3.1.6\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-04-21T16:11:50.875542Z\",\"id\":\"CVE-2026-5450\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"total\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"3ff69d7a-14f2-4f67-a097-88dee7810d18\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-122\"}]},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-787\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:gnu:glibc:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.7\",\"versionEndIncluding\":\"2.43\",\"matchCriteriaId\":\"36C44C9A-5EBA-4114-8379-A022AE49F18E\"}]}]}],\"references\":[{\"url\":\"https://inbox.sourceware.org/libc-announce/b11f0003-6ec1-4bd6-b9de-9e38a4efeca3@redhat.com/T/#u\",\"source\":\"3ff69d7a-14f2-4f67-a097-88dee7810d18\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450\",\"source\":\"3ff69d7a-14f2-4f67-a097-88dee7810d18\",\"tags\":[\"Exploit\",\"Issue Tracking\"]},{\"url\":\"https://cert-portal.siemens.com/productcert/html/ssa-082556.html\",\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\"},{\"url\":\"https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"tags\":[\"Exploit\",\"Issue Tracking\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-08T15:43:15+00:00",
      "cve": "CVE-2026-5450",
      "id": "CVE-2026-5450",
      "initial_release_date": "2026-04-20T20:55:41.170000+00:00",
      "product_status:fixed": "8749",
      "product_status:known_affected": "3",
      "product_status:known_not_affected": "7",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "glibc: glibc: Heap Buffer Overflow in `scanf` with `%mc` format specifier and large width",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5450.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-16T00:17:11Z",
      "cve": "CVE-2026-5450",
      "id": "CVE-2026-5450",
      "initial_release_date": "2026-04-22T01:40:40Z",
      "product_status:first_fixed": "1",
      "product_status:known_affected": "604",
      "product_status:recommended": "1083",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-5450",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-5450.json",
      "version": "33"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 9.8, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-5450\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-04-21T16:11:50.875542Z\"}}}], \"references\": [{\"url\": \"https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-04-21T16:04:17.997Z\"}}], \"cna\": {\"title\": \"scanf %mc off-by-one heap buffer overflow\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Rocket Ma\"}], \"impacts\": [{\"capecId\": \"CAPEC-100\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-100 Overflow Buffers\"}]}], \"affected\": [{\"vendor\": \"The GNU C Library\", \"product\": \"glibc\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unaffected\"}], \"datePublic\": \"2026-03-19T17:36:00.000Z\", \"references\": [{\"url\": \"https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450\", \"tags\": [\"issue-tracking\"]}, {\"url\": \"https://inbox.sourceware.org/libc-announce/b11f0003-6ec1-4bd6-b9de-9e38a4efeca3@redhat.com/T/#u\", \"tags\": [\"mailing-list\"]}], \"x_generator\": {\"engine\": \"Vulnogram 1.0.1\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Calling the scanf family of functions with a %mc (malloc\u0027d character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Calling the scanf family of functions with a %mc (malloc\u0027d character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-122\", \"description\": \"CWE-122 Heap-based buffer overflow\"}]}], \"providerMetadata\": {\"orgId\": \"3ff69d7a-14f2-4f67-a097-88dee7810d18\", \"shortName\": \"glibc\", \"dateUpdated\": \"2026-04-20T20:55:41.170Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-5450\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-21T19:49:53.221Z\", \"dateReserved\": \"2026-04-02T21:47:21.403Z\", \"assignerOrgId\": \"3ff69d7a-14f2-4f67-a097-88dee7810d18\", \"datePublished\": \"2026-04-20T20:55:41.170Z\", \"assignerShortName\": \"glibc\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.


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.