Nixpkgs security tracker

Login with GitHub
⚠️ You are using a production deployment that is still only suitable for demo purposes. Any work done in this might be wiped later without notice.

Suggestion detail

Untriaged
created 1 month, 1 week ago Activity log
  • Created suggestion
YAML::Syck versions before 1.47 for Perl allow a use-after-free and double-free via an anchor node freed while still on the parser value stack

YAML::Syck versions before 1.47 for Perl allow a use-after-free and double-free via an anchor node freed while still on the parser value stack. In the bundled libsyck, when an anchor name is redefined or removed, syck_hdlr_add_anchor and syck_hdlr_remove_anchor free the node stored under that name with syck_free_node. That node can still be live on the parser's value stack, so syck_hdlr_add_node reaches it again and frees it a second time. On a normal build the 48-byte node chunk is freed twice and the interpreter aborts. Anchors need no special flags, so this is reached on the default Load path, and a 7-byte document that redefines an anchor triggers it. Any caller that runs Load or LoadFile on an untrusted document that redefines an anchor mid-parse crashes the interpreter, a denial of service.

Affected products

YAML-Syck
  • <1.47

Matching in nixpkgs

pkgs.perlPackages.YAMLSyck

Fast, lightweight YAML loader and dumper

  • nixos-unstable -
    • nixos-unstable-small 1.45
  • nixos-26.05 -
    • nixos-26.05-small 1.45

pkgs.perl5Packages.YAMLSyck

Fast, lightweight YAML loader and dumper

  • nixos-unstable -
    • nixos-unstable-small 1.45
  • nixos-26.05 -
    • nixos-26.05-small 1.45