CVE-2021-29991

EPSS 0.9%

Vexday Risk Score

3Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS —EPSS 0.9%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

03 Nov 2021Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Firefox incorrectly accepted a newline in a HTTP/3 header, interpretting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3. This vulnerability affects Firefox < 91.0.1 and Thunderbird < 91.0.1.

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=1724896 https://www.mozilla.org/security/advisories/mfsa2021-37/