Mercurial before version 4.6.1 has a missing check for fragment start position in mpatch.c:mpatch_apply() Upstream Changelog: https://www.mercurial-scm.org/wiki/WhatsNew#Mercurial_4.6.1_.282018-06-06.29 Upstream Patch: https://www.mercurial-scm.org/repo/hg/rev/faa924469635
This is related to CVE-2018-13347: this issue is reading past the end of input where the other writes before the output buffer. In mercurial 2.6.2, it is present in the apply() function.
Created mercurial tracking bugs for this issue: Affects: fedora-all [bug 1594088]
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2019:2276 https://access.redhat.com/errata/RHSA-2019:2276
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2018-13346