CVE-2020-26961
First published: Tue Nov 17 2020(Updated: )
When DNS over HTTPS is in use, it intentionally filters RFC1918 and related IP ranges from the responses as these do not make sense coming from a DoH resolver. However when an IPv4 address was mapped through IPv6, these addresses were erroneously let through, leading to a potential DNS Rebinding attack.
Credit: security@mozilla.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Mozilla Firefox ESR | <78.5 | 78.5 |
| <83 | 83 | |
| <78.5 | 78.5 | |
| <78.5 | 78.5 | |
| Mozilla Firefox | <83.0 | |
| Mozilla Firefox ESR | <78.5 | |
| Mozilla Thunderbird | <78.5 |
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Reference Links
- https://bugzilla.mozilla.org/show_bug.cgi?id=1672528
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-51/
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-50/
- https://www.mozilla.org/en-US/security/advisories/mfsa2020-52/
- https://www.mozilla.org/security/advisories/mfsa2020-50/
- https://www.mozilla.org/security/advisories/mfsa2020-51/
- https://www.mozilla.org/security/advisories/mfsa2020-52/
Peer vulnerabilities
(Found alongside the following vulnerabilities)
Frequently Asked Questions
What is CVE-2020-26961?
CVE-2020-26961 is a vulnerability related to DNS over HTTPS (DoH) in Mozilla products, including Firefox ESR, Thunderbird, and Firefox.
What is the severity of CVE-2020-26961?
CVE-2020-26961 has a severity rating of 6.5 (Medium).
Which software versions are affected by CVE-2020-26961?
Mozilla Firefox ESR versions up to and excluding 78.5, Mozilla Thunderbird versions up to and excluding 78.5, and Mozilla Firefox versions up to and excluding 83.0 are affected by CVE-2020-26961.
How does CVE-2020-26961 impact DNS over HTTPS (DoH)?
CVE-2020-26961 allows IPv4 addresses mapped through IPv6 to bypass the intentional filtering of RFC1918 and related IP ranges in DoH, potentially leading to a DNS Rebinding attack.
How can I fix CVE-2020-26961?
To fix CVE-2020-26961, update your Mozilla Firefox ESR to version 78.5 and Thunderbird to version 78.5, or update Mozilla Firefox to version 83.0 or newer.
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