url.cpp in libproxy through 0.4.15 is prone to a buffer overflow when PAC is enabled, as demonstrated by a large PAC file that is delivered without a Content-length header.
lists.opensuse.org/opensuse-security-announce/2020-10/msg00030.html
lists.opensuse.org/opensuse-security-announce/2020-10/msg00033.html
bugs.debian.org/968366
github.com/libproxy/libproxy/pull/126
lists.debian.org/debian-lts-announce/2020/11/msg00024.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3BID3HVHAF6DA3YJOFDBSAZSMR3ODNIW/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WZVZXTFMFTSML3J6OOCDBDYH474BRJSW/
www.debian.org/security/2020/dsa-4800