| Name | CVE-2021-4209 |
| Description | A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-3070-1, ELA-1090-1 |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| gnutls28 (PTS) | jessie, jessie (lts) | 3.3.30-0+deb8u2 | fixed |
| stretch (security) | 3.5.8-5+deb9u6 | vulnerable |
| stretch (lts), stretch | 3.5.8-5+deb9u7 | fixed |
| buster (security), buster, buster (lts) | 3.6.7-4+deb10u12 | fixed |
| bullseye | 3.7.1-5+deb11u5 | fixed |
| bullseye (security) | 3.7.1-5+deb11u6 | fixed |
| bookworm | 3.7.9-2+deb12u3 | fixed |
| sid, trixie | 3.8.8-2 | fixed |
The information below is based on the following data on fixed versions.
Notes
[stretch] - gnutls28 <postponed> (Minor issue)
https://bugzilla.redhat.com/show_bug.cgi?id=2044156
https://gitlab.com/gnutls/gnutls/-/issues/1306
https://gitlab.com/gnutls/gnutls/-/merge_requests/1503
Fixed by: https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568 (3.7.3)
[jessie] - gnutls28 <not-affected> (Vulnerable not used - see below)
For Jessie the vulnerability is not present when nettle2 is used (as it is in Jessie)
The code used in this case prevents the vulnerability: https://salsa.debian.org/lts-team/packages/gnutls28/-/blob/e7577e323e594ae0eba4f481de05044ca969e4ff/lib/nettle/gnettle.h#L20