noweb is a simple, extensible, and language independent literate programming tool.
Javier Fernandez-Sanguino has discovered that the lib/toascii.nw and shell/roff.mm scripts insecurely create temporary files with predictable filenames.
A local attacker could create symbolic links in the temporary file directory, pointing to a valid file somewhere on the filesystem. When an affected script is called, this would result in the file being overwritten with the rights of the user running the script.
There is no known workaround at this time.
All noweb users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-text/noweb-2.9-r5"