USN-5047-1: Firefox vulnerability

Releases

• Ubuntu 21.04
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM

Packages

• firefox - Mozilla Open Source web browser

Details

It was discovered that Firefox could be made to incorrectly accept
newlines in HTTP/3 response headers. If a user were tricked into
opening a specially crafted website, an attacker could exploit this
to conduct header splitting attacks.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.04

• firefox - 91.0.1+build1-0ubuntu0.21.04.1

Ubuntu 20.04

• firefox - 91.0.1+build1-0ubuntu0.20.04.1

Ubuntu 18.04

• firefox - 91.0.1+build1-0ubuntu0.18.04.1

After a standard system update you need to restart Firefox to make
all the necessary changes.

References

• CVE-2021-29991

Related notices

• USN-5248-1: thunderbird-locale-ca, thunderbird-locale-nb, thunderbird-locale-it, thunderbird-locale-da, thunderbird-locale-en, thunderbird-locale-fr, thunderbird-locale-en-gb, thunderbird-locale-be, thunderbird-locale-pt, thunderbird-locale-ast, thunderbird-locale-uz, thunderbird-locale-ar, thunderbird-locale-hsb, thunderbird-locale-ga, thunderbird-locale-ka, thunderbird-locale-lv, thunderbird-locale-fi, thunderbird-locale-cak, thunderbird-locale-en-us, thunderbird-locale-th, thunderbird-locale-kab, thunderbird-locale-zh-tw, xul-ext-lightning, thunderbird-locale-nl, thunderbird-locale-ja, thunderbird-mozsymbols, thunderbird-locale-gl, thunderbird-locale-fy-nl, thunderbird-locale-tr, thunderbird-locale-zh-cn, thunderbird-locale-si, thunderbird-locale-hy, thunderbird, thunderbird-locale-dsb, thunderbird-locale-sk, thunderbird-locale-af, thunderbird-locale-kk, thunderbird-locale-bn, thunderbird-locale-sr, thunderbird-locale-bn-bd, thunderbird-locale-es, thunderbird-locale-pt-pt, thunderbird-locale-sl, xul-ext-gdata-provider, thunderbird-locale-br, thunderbird-locale-cs, thunderbird-locale-rm, thunderbird-locale-eu, thunderbird-locale-he, thunderbird-locale-ga-ie, thunderbird-locale-ro, thunderbird-locale-el, thunderbird-locale-bg, thunderbird-locale-de, thunderbird-locale-sv, thunderbird-locale-hu, thunderbird-locale-et, thunderbird-gnome-support, thunderbird-locale-cy, thunderbird-locale-zh-hans, thunderbird-locale-is, thunderbird-locale-sv-se, thunderbird-locale-pa, thunderbird-locale-id, thunderbird-locale-fa, xul-ext-calendar-timezones, thunderbird-locale-es-ar, thunderbird-locale-es-es, thunderbird-locale-sq, thunderbird-locale-uk, thunderbird-locale-hr, thunderbird-locale-vi, thunderbird-locale-zh-hant, thunderbird-locale-mk, thunderbird-locale-nb-no, thunderbird-locale-pl, thunderbird-locale-fy, thunderbird-locale-ko, thunderbird-locale-ru, thunderbird-locale-pa-in, thunderbird-locale-ta, thunderbird-dev, thunderbird-locale-ta-lk, thunderbird-locale-nn, thunderbird-locale-ms, thunderbird-locale-lt, thunderbird-locale-nn-no, thunderbird-locale-gd, thunderbird-locale-pt-br