A libspf2 security update has been released for Debian GNU/Linux 10 to address a stack-based buffer overflow.

DSA 4955-1: libspf2 security update

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Debian Security Advisory DSA-4955-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
August 11, 2021   https://www.debian.org/security/faq
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Package : libspf2
CVE ID : CVE-2021-20314

Philipp Jeitner and Haya Shulman discovered a stack-based buffer
overflow in libspf2, a library for validating mail senders with SPF,
which could result in denial of service, or potentially execution of
arbitrary code when processing a specially crafted SPF record.

For the stable distribution (buster), this problem has been fixed in
version 1.2.10-7.1~deb10u1.

We recommend that you upgrade your libspf2 packages.

For the detailed security status of libspf2 please refer to its security
tracker page at:
  https://security-tracker.debian.org/tracker/libspf2

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/