Vulnerability-Lookup

FKIE_CVE-2026-86415

Vulnerability from fkie_nvd - Published: 2026-10-20 21:17 - Updated: 2026-10-20 21:17

Severity

Summary

libcurl's connection cache match function never considers the automatic client certificate option, so a cached, already authenticated Schannel connection can be handed to a transfer that got redirected to a different origin, even though the code explicitly switched off the auto client cert option for that transfer to prevent exactly this.

References

	URL	Tags
	2499f714-1537-4658-8207-48ae4bb9eae9	https://curl.se/docs/CVE-2026-86415.html
	2499f714-1537-4658-8207-48ae4bb9eae9	https://curl.se/docs/CVE-2026-86415.json
	2499f714-1537-4658-8207-48ae4bb9eae9	https://hackerone.com/reports/3993870

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThanOrEqual": "8.22.0",
              "status": "affected",
              "version": "8.22.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.21.0",
              "status": "affected",
              "version": "8.21.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "libcurl\u0027s connection cache match function never considers the automatic client\ncertificate option, so a cached, already authenticated Schannel connection can\nbe handed to a transfer that got redirected to a different origin, even though\nthe code explicitly switched off the auto client cert option for that transfer\nto prevent exactly this."
    }
  ],
  "id": "CVE-2026-86415",
  "lastModified": "2026-10-20T21:17:20.067",
  "metrics": {},
  "published": "2026-10-20T21:17:20.067",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://curl.se/docs/CVE-2026-86415.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://curl.se/docs/CVE-2026-86415.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "url": "https://hackerone.com/reports/3993870"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Received"
}

CVE-2026-86415 (GCVE-0-2026-86415)

Vulnerability from cvelistv5 – Published: 2026-10-20 20:08 – Updated: 2026-10-20 20:08

Title

auto client cert connection reuse mixup

Summary

Severity

No CVSS data available.

CWE

CWE-201 Information Exposure Through Sent Data

Assigner

curl CNA under the redhat root

CNA scorecard D 46/100 over 59 records in the last 180 days details

References

3 references

URL	Tags
https://curl.se/docs/CVE-2026-86415.json
https://curl.se/docs/CVE-2026-86415.html
https://hackerone.com/reports/3993870

Impacted products

1 product

Vendor	Product	Version
curl	curl	Affected: 8.22.0 , ≤ 8.22.0 (semver) Affected: 8.21.0 , ≤ 8.21.0 (semver)

Credits

Stanislav Fort (Aisle Research) Stefan Eissing

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThanOrEqual": "8.22.0",
              "status": "affected",
              "version": "8.22.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.21.0",
              "status": "affected",
              "version": "8.21.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Stanislav Fort (Aisle Research)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Stefan Eissing"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "libcurl\u0027s connection cache match function never considers the automatic client\ncertificate option, so a cached, already authenticated Schannel connection can\nbe handed to a transfer that got redirected to a different origin, even though\nthe code explicitly switched off the auto client cert option for that transfer\nto prevent exactly this."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-201 Information Exposure Through Sent Data",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-20T20:08:29.941Z",
        "orgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "shortName": "curl"
      },
      "references": [
        {
          "name": "json",
          "url": "https://curl.se/docs/CVE-2026-86415.json"
        },
        {
          "name": "www",
          "url": "https://curl.se/docs/CVE-2026-86415.html"
        },
        {
          "name": "issue",
          "url": "https://hackerone.com/reports/3993870"
        }
      ],
      "title": "auto client cert connection reuse mixup"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
    "assignerShortName": "curl",
    "cveId": "CVE-2026-86415",
    "datePublished": "2026-10-20T20:08:29.941Z",
    "dateReserved": "2026-09-07T12:11:55.106Z",
    "dateUpdated": "2026-10-20T20:08:29.941Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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

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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.

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