CVE-2026-1299 (GCVE-0-2026-1299)

Vulnerability from cvelistv5 – Published: 2026-01-23 16:27 – Updated: 2026-01-26 14:20
VLAI?
Title
email BytesGenerator header injection due to unquoted newlines
Summary
The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding rules, the new behavior will reject the incorrectly folded headers in "BytesGenerator".
Severity ?
6 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
CWE
Assigner
PSF
References
Impacted products
Vendor Product Version
Python Software Foundation CPython Affected: 0 , < 3.15.0 (python)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-1299",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-01-23T16:55:59.722632Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-01-23T16:56:22.155Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "email"
          ],
          "product": "CPython",
          "repo": "https://github.com/python/cpython",
          "vendor": "Python Software Foundation",
          "versions": [
            {
              "lessThan": "3.15.0",
              "status": "affected",
              "version": "0",
              "versionType": "python"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "The \nemail module, specifically the \"BytesGenerator\" class, didn\u2019t properly quote newlines for email headers when \nserializing an email message allowing for header injection when an email\n is serialized. This is only applicable if using \"LiteralHeader\" writing headers that don\u0027t respect email folding rules, the new behavior will reject the incorrectly folded headers in \"BytesGenerator\"."
            }
          ],
          "value": "The \nemail module, specifically the \"BytesGenerator\" class, didn\u2019t properly quote newlines for email headers when \nserializing an email message allowing for header injection when an email\n is serialized. This is only applicable if using \"LiteralHeader\" writing headers that don\u0027t respect email folding rules, the new behavior will reject the incorrectly folded headers in \"BytesGenerator\"."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-93",
              "description": "CWE-93",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-26T14:20:21.976Z",
        "orgId": "28c92f92-d60d-412d-b760-e73465c3df22",
        "shortName": "PSF"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/pull/144126"
        },
        {
          "tags": [
            "issue-tracking"
          ],
          "url": "https://github.com/python/cpython/issues/144125"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://cve.org/CVERecord?id=CVE-2024-6923"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/6ZZULGALJTITEAGEXLDJE2C6FORDXPBT/"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/7877fe424415bc4a13045e62a90a7277413d8cb9"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/842ce19a0c0b58d61591e8f6a708c38db1fb94e4"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/python/cpython/commit/8cdf6204f4ae821f32993f8fc6bad0d318f95f36"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "email BytesGenerator header injection due to unquoted newlines",
      "x_generator": {
        "engine": "Vulnogram 0.5.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "28c92f92-d60d-412d-b760-e73465c3df22",
    "assignerShortName": "PSF",
    "cveId": "CVE-2026-1299",
    "datePublished": "2026-01-23T16:27:13.346Z",
    "dateReserved": "2026-01-21T18:30:52.594Z",
    "dateUpdated": "2026-01-26T14:20:21.976Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-1299\",\"sourceIdentifier\":\"cna@python.org\",\"published\":\"2026-01-23T17:16:12.977\",\"lastModified\":\"2026-01-26T15:16:07.237\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"The \\nemail module, specifically the \\\"BytesGenerator\\\" class, didn\u2019t properly quote newlines for email headers when \\nserializing an email message allowing for header injection when an email\\n is serialized. This is only applicable if using \\\"LiteralHeader\\\" writing headers that don\u0027t respect email folding rules, the new behavior will reject the incorrectly folded headers in \\\"BytesGenerator\\\".\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"cna@python.org\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":6.0,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"LOW\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"cna@python.org\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-93\"}]}],\"references\":[{\"url\":\"https://cve.org/CVERecord?id=CVE-2024-6923\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/commit/7877fe424415bc4a13045e62a90a7277413d8cb9\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/commit/842ce19a0c0b58d61591e8f6a708c38db1fb94e4\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/commit/8cdf6204f4ae821f32993f8fc6bad0d318f95f36\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/issues/144125\",\"source\":\"cna@python.org\"},{\"url\":\"https://github.com/python/cpython/pull/144126\",\"source\":\"cna@python.org\"},{\"url\":\"https://mail.python.org/archives/list/security-announce@python.org/thread/6ZZULGALJTITEAGEXLDJE2C6FORDXPBT/\",\"source\":\"cna@python.org\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-1299\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-01-23T16:55:59.722632Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-01-23T16:56:16.248Z\"}}], \"cna\": {\"title\": \"email BytesGenerator header injection due to unquoted newlines\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"LOW\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"HIGH\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"LOW\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"repo\": \"https://github.com/python/cpython\", \"vendor\": \"Python Software Foundation\", \"modules\": [\"email\"], \"product\": \"CPython\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"3.15.0\", \"versionType\": \"python\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/python/cpython/pull/144126\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/python/cpython/issues/144125\", \"tags\": [\"issue-tracking\"]}, {\"url\": \"https://cve.org/CVERecord?id=CVE-2024-6923\", \"tags\": [\"related\"]}, {\"url\": \"https://mail.python.org/archives/list/security-announce@python.org/thread/6ZZULGALJTITEAGEXLDJE2C6FORDXPBT/\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/python/cpython/commit/7877fe424415bc4a13045e62a90a7277413d8cb9\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/python/cpython/commit/842ce19a0c0b58d61591e8f6a708c38db1fb94e4\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/python/cpython/commit/8cdf6204f4ae821f32993f8fc6bad0d318f95f36\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.5.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"The \\nemail module, specifically the \\\"BytesGenerator\\\" class, didn\\u2019t properly quote newlines for email headers when \\nserializing an email message allowing for header injection when an email\\n is serialized. This is only applicable if using \\\"LiteralHeader\\\" writing headers that don\u0027t respect email folding rules, the new behavior will reject the incorrectly folded headers in \\\"BytesGenerator\\\".\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"The \\nemail module, specifically the \\\"BytesGenerator\\\" class, didn\\u2019t properly quote newlines for email headers when \\nserializing an email message allowing for header injection when an email\\n is serialized. This is only applicable if using \\\"LiteralHeader\\\" writing headers that don\u0027t respect email folding rules, the new behavior will reject the incorrectly folded headers in \\\"BytesGenerator\\\".\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-93\", \"description\": \"CWE-93\"}]}], \"providerMetadata\": {\"orgId\": \"28c92f92-d60d-412d-b760-e73465c3df22\", \"shortName\": \"PSF\", \"dateUpdated\": \"2026-01-26T14:20:21.976Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-1299\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-26T14:20:21.976Z\", \"dateReserved\": \"2026-01-21T18:30:52.594Z\", \"assignerOrgId\": \"28c92f92-d60d-412d-b760-e73465c3df22\", \"datePublished\": \"2026-01-23T16:27:13.346Z\", \"assignerShortName\": \"PSF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

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.