CVE-2021-21323
CVE-2021-21323 — Regression in DNS leakage from Tor windows
Brave is an open source web browser with a focus on privacy and security. In Brave versions 1.17.73-1.20.103, the CNAME adblocking feature added in Brave 1.17.73 accidentally initiated DNS requests that bypassed the Brave Tor proxy. Users with adblocking enabled would leak DNS requests from Tor windows to their DNS provider. (DNS requests that were not initiated by CNAME adblocking would go through Tor as expected.) This is fixed in Brave version 1.20.108
Published Updated Sources: cvelistV5, GitHub_M
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
2%
chance of exploitation in 30 days
CVSS base
4.3
MEDIUM
Affected scope
The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.
Vendors (1)
Products (1)
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 4.3 | CVSS 3.1 | MEDIUM | — | — | cvelistV5 |
Weakness & attack patterns
- CWE-200
Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.
- T1562.003Impair Defenses: Impair Command History Logging
- T1574.006Hijack Execution Flow: Dynamic Linker Hijacking
- T1574.007Hijack Execution Flow: Path Interception by PATH Environment Variable
References
5 on the record
- github.com/brave/brave-browser/security/advisories/GHSA-mqjf-9x5g-2rv6
x_refsource_CONFIRM
- github.com/brave/brave-browser/issues/13527
x_refsource_MISC
- github.com/brave/brave-core/pull/7769
x_refsource_MISC
- github.com/brave/brave-core/commit/12fe321eaad8acc1cbd1d70b4128f687777bcf15
x_refsource_MISC
- hackerone.com/reports/1077022
x_refsource_MISC
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.