CVE-2026-126133 (GCVE-0-2026-126133)

Vulnerability from cvelistv5 – Published: 2026-11-10 18:59 – Updated: 2026-11-10 20:24
VLAI
Title
Calendar server credentials could be sent to an HTTP proxy
Summary
When a CalDAV or ICS calendar was accessed through an HTTP proxy that requested authentication, Thunderbird could answer the proxy with the calendar server's username and password. This affected both setting up a new calendar and syncing existing calendars, where a saved password could be sent without any user interaction. A malicious or compromised proxy could use this to obtain the calendar credentials, even for calendars served over HTTPS. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7.
Severity
No CVSS data available.
Assigner
mozilla CNA
References
Impacted products
Vendor Product Version
Mozilla Thunderbird Unaffected: 153.7 , ≤ 153.* (rpm)
Unaffected: 160 , ≤ * (rpm)
Create a notification for this product.
Credits
Christopher Bohn (Protectstar Inc.)
Show details on NVD website
To clipboard 

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  "containers": {
    "cna": {
      "affected": [
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThanOrEqual": "153.*",
              "status": "unaffected",
              "version": "153.7",
              "versionType": "rpm"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "160",
              "versionType": "rpm"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Christopher Bohn (Protectstar Inc.)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "When a CalDAV or ICS calendar was accessed through an HTTP proxy that requested authentication, Thunderbird could answer the proxy with the calendar server\u0027s username and password. This affected both setting up a new calendar and syncing existing calendars, where a saved password could be sent without any user interaction. A malicious or compromised proxy could use this to obtain the calendar credentials, even for calendars served over HTTPS. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7."
            }
          ],
          "value": "When a CalDAV or ICS calendar was accessed through an HTTP proxy that requested authentication, Thunderbird could answer the proxy with the calendar server\u0027s username and password. This affected both setting up a new calendar and syncing existing calendars, where a saved password could be sent without any user interaction. A malicious or compromised proxy could use this to obtain the calendar credentials, even for calendars served over HTTPS. This vulnerability was fixed in Thunderbird 160 and Thunderbird 153.7."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-10T20:24:06.988Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2083485"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-128/"
        },
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2026-129/"
        }
      ],
      "title": "Calendar server credentials could be sent to an HTTP proxy"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2026-126133",
    "datePublished": "2026-11-10T18:59:54.427Z",
    "dateReserved": "2026-11-10T18:59:53.798Z",
    "dateUpdated": "2026-11-10T20:24:06.988Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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