The S/MIME specification allows a Cipher Block Chaining (CBC) malleability-gadget attack that can indirectly lead to plaintext exfiltration, aka EFAIL.
There is a stack-based buffer over-read in calling GLib in the function gxps_images_guess_content_type of gxps-images.c in libgxps through 0.3.0 because it does not reject negative return values from a g_input_stream_read call. A crafted input will lead to a remote denial of service attack.
There is a heap-based buffer over-read in the function ft_font_face_hash of gxps-fonts.c in libgxps through 0.3.0. A crafted input will lead to a remote denial of service attack.
An exploitable stack based buffer overflow vulnerability exists in the GNOME libsoup 2.58. A specially crafted HTTP request can cause a stack overflow resulting in remote code execution. An attacker can send a special HTTP request to the vulnerable server to trigger this vulnerability.
GNOME NetworkManager version 1.10.2 and earlier contains a Information Exposure (CWE-200) vulnerability in DNS resolver that can result in Private DNS queries leaked to local network's DNS servers, while on VPN. This vulnerability appears to have been fixed in Some Ubuntu 16.04 packages were fixed, but later updates removed the fix. cf. https://bugs.launchpad.net/ubuntu/+bug/1754671 an upstream fix does not appear to be available at this time.
GNOME librsvg version before commit c6ddf2ed4d768fd88adbea2b63f575cd523022ea contains a Improper input validation vulnerability in rsvg-io.c that can result in the victim's Windows username and NTLM password hash being leaked to remote attackers through SMB. This attack appear to be exploitable via The victim must process a specially crafted SVG file containing an UNC path on Windows.
A stack-based buffer overflow within GNOME gcab through 0.7.4 can be exploited by malicious attackers to cause a crash or, potentially, execute arbitrary code via a crafted .cab file.
Gnome gdk-pixbuf 2.36.8 and older is vulnerable to several integer overflow in the gif_get_lzw function resulting in memory corruption and potential code execution
GNOME Nautilus before 3.23.90 allows attackers to spoof a file type by using the .desktop file extension, as demonstrated by an attack in which a .desktop file's Name field ends in .pdf but this file's Exec field launches a malicious "sh -c" command. In other words, Nautilus provides no UI indication that a file actually has the potentially unsafe .desktop extension; instead, the UI only shows the .pdf extension. One (slightly) mitigating factor is that an attack requires the .desktop file to have execute permission. The solution is to ask the user to confirm that the file is supposed to be treated as a .desktop file, and then remember the user's answer in the metadata::trusted field.