FKIE_CVE-2021-43541
Vulnerability from fkie_nvd - Published: 2021-12-08 22:15 - Updated: 2026-06-17 04:11
Severity
Summary
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| mozilla | firefox | * | |
| mozilla | firefox_esr | * | |
| mozilla | thunderbird | * | |
| debian | debian_linux | 9.0 | |
| debian | debian_linux | 10.0 | |
| debian | debian_linux | 11.0 |
{
"affected": [
{
"affectedData": [
{
"product": "Thunderbird",
"vendor": "Mozilla",
"versions": [
{
"lessThan": "91.4.0",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
},
{
"product": "Firefox ESR",
"vendor": "Mozilla",
"versions": [
{
"lessThan": "91.4.0",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
},
{
"product": "Firefox",
"vendor": "Mozilla",
"versions": [
{
"lessThan": "95",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
}
],
"source": "security@mozilla.org"
}
],
"configurations": [
{
"nodes": [
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"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
"matchCriteriaId": "83D69E34-EB94-49ED-9FA1-F68400971726",
"versionEndExcluding": "95.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*",
"matchCriteriaId": "F90A171C-1670-4EBA-9DE0-E31E8F3CD0FA",
"versionEndExcluding": "91.4.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
"matchCriteriaId": "6F0BE95D-5BE5-49F7-92BA-CF3A3920D447",
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"negate": false,
"operator": "OR"
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]
},
{
"nodes": [
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"matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252",
"vulnerable": true
},
{
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],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird \u003c 91.4.0, Firefox ESR \u003c 91.4.0, and Firefox \u003c 95."
},
{
"lang": "es",
"value": "Cuando son invocados manejadores de protocolo para protocolos externos, una URL de par\u00e1metro suministrada que conten\u00eda espacios no se escapaba correctamente. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 91.4.0, Firefox ESR versiones anteriores a 91.4.0 y Firefox versiones anteriores a 95"
}
],
"id": "CVE-2021-43541",
"lastModified": "2026-06-17T04:11:05.957",
"metrics": {
"cvssMetricV2": [
{
"acInsufInfo": false,
"baseSeverity": "MEDIUM",
"cvssData": {
"accessComplexity": "MEDIUM",
"accessVector": "NETWORK",
"authentication": "NONE",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"confidentialityImpact": "NONE",
"integrityImpact": "PARTIAL",
"vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
"version": "2.0"
},
"exploitabilityScore": 8.6,
"impactScore": 2.9,
"obtainAllPrivilege": false,
"obtainOtherPrivilege": false,
"obtainUserPrivilege": false,
"source": "nvd@nist.gov",
"type": "Primary",
"userInteractionRequired": true
}
],
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
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"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
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"source": "nvd@nist.gov",
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"published": "2021-12-08T22:15:09.840",
"references": [
{
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"tags": [
"Issue Tracking",
"Permissions Required",
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],
"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1696685"
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},
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},
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{
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},
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{
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{
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"url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
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"sourceIdentifier": "security@mozilla.org",
"vulnStatus": "Modified",
"weaknesses": [
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"lang": "en",
"value": "NVD-CWE-Other"
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"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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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.
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.
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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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