MRMCD 2026

Until May 2025, I liked PGP, and the GNU Privacy Guard. I poked at it in my free time a lot. One day, that suddenly changed, when I flew too close to the sun and ended up uncovering a vulnerability that allows you to easily spoof a PGP signature when opened naively with the GPG tool.

Fast-forward a couple of months, the one vulnerability turned into several independent ones, up to memory corruption in the basic PGP message parser, affecting almost all PGP-related workflows.

I disclosed these a few weeks before 39c3 in December 2025. And while some of the vulnerabilities - like the memory corruption in the message parser - got addressed properly, this was not the case for all of them.

For example, one of the first vulnerabilities I found, that was used for the introduction hook in the 39c3 talk, remains unpatched to this day. Instead of being fixed with code, Werner Koch - the main developer of GnuPG - published a blog post declaring the widely-used feature being "harmful"; while they had weeks in advance, they published this on day one of 39c3, not even giving us time to respond.

Several disgruntled comments followed, but a good portion of the flaws are still not addressed, as I will demonstrate live in the talk. This specific demonstration will not utilize any zero-day vulnerabilities (those come next); we will be showing how much of an issue the footguns (that they refuse to address) at hand really are.

Additionally, I will present a few novel vulnerabilities on GPG. Not quite the bombshells as last time, but some nifty bugs that should never have made it into production in the first place, but to demonstrate the state of the GnuPG codebase.

The talk closes with some general commentary about the state of security and responsible disclosure, and touch on the topic of AI/LLMs in security (with some of the gpg.fail vulnerabilities as examples); what this means for security researchers, ordinary people and software developers (spoiler: neither end users nor security researchers are doomed).