Researchers Discover Vulnerabilities in PGP/GPG Email Encryption Plugins, Users Advised to Avoid for Now

A warning has been issued by European security researchers about critical vulnerabilities discovered in PGP/GPG and S/MIME email encryption software that could reveal the plaintext of encrypted emails, including encrypted messages sent in the past.

GPGMail pane
The alert was put out late on Sunday night by professor of computer security Sebastian Schinzel. A joint research paper, due to be published tomorrow at 07:00 a.m. UTC (3:00 a.m. Eastern Time, 12:00 am Pacific) promises to offer a thorough explanation of the vulnerabilities, for which there are currently no reliable fixes.


Details remain vague about the so-called "Efail" exploit, but it appears to involve an attack vector on the encryption implementation in the client software as it processes HTML, rather than a vulnerability in the encryption method itself. A blog post published late Sunday night by the Electronic Frontier Foundation said:

"EFF has been in communication with the research team, and can confirm that these vulnerabilities pose an immediate risk to those using these tools for email communication, including the potential exposure of the contents of past messages."

In the meantime, users of PGP/GPG and S/MIME are being advised to immediately disable and/or uninstall tools that automatically decrypt PGP-encrypted email, and seek alternative end-to-end encrypted channels such as Signal to send and receive sensitive content.

Update: The GPGTools/GPGMail team has posted a temporary workaround against the vulnerability, while MacRumors has compiled a separate guide to removing the popular open source plugin for Apple Mail until a fix for the vulnerability is released. Other popular affected clients include Mozilla Thunderbird with Enigmail and Microsoft Outlook with GPG4win. Click the links for EFF's uninstall steps.

Popular Stories

iOS 26

iOS 26.2 Coming Soon With These 8 New Features on Your iPhone

Thursday December 11, 2025 8:49 am PST by
Apple seeded the second iOS 26.2 Release Candidate to developers earlier this week, meaning the update will be released to the general public very soon. Apple confirmed iOS 26.2 would be released in December, but it did not provide a specific date. We expect the update to be released by early next week. iOS 26.2 includes a handful of new features and changes on the iPhone, such as a new...
Google maps feaure

Google Maps Quietly Added This Long-Overdue Feature for Drivers

Wednesday December 10, 2025 2:52 am PST by
Google Maps on iOS quietly gained a new feature recently that automatically recognizes where you've parked your vehicle and saves the location for you. Announced on LinkedIn by Rio Akasaka, Google Maps' senior product manager, the new feature auto-detects your parked location even if you don't use the parking pin function, saves it for up to 48 hours, and then automatically removes it once...
AirPods Pro Firmware Feature

Apple Releases New Firmware for AirPods Pro 2 and AirPods Pro 3

Thursday December 11, 2025 11:28 am PST by
Apple today released new firmware designed for the AirPods Pro 3 and the prior-generation AirPods Pro 2. The AirPods Pro 3 firmware is 8B30, up from 8B25, while the AirPods Pro 2 firmware is 8B28, up from 8B21. There's no word on what's include in the updated firmware, but the AirPods Pro 2 and AirPods Pro 3 are getting expanded support for Live Translation in the European Union in iOS...
iOS 26

iOS 26.4 and iOS 27 Features Revealed in New Leak

Friday December 12, 2025 10:56 am PST by
Macworld's Filipe Espósito today revealed a handful of features that Apple is allegedly planning for iOS 26.4, iOS 27, and even iOS 28. The report said the features are referenced within the code for a leaked internal build of iOS 26 that is not meant to be seen by the public. However, it appears that Espósito and/or his sources managed to gain access to it, providing us with a sneak peek...
Foldable iPhone 2023 Feature 1

Apple to Make More Foldable iPhones Than Expected [Updated]

Tuesday December 9, 2025 9:59 am PST by
Apple has ordered 22 million OLED panels from Samsung Display for the first foldable iPhone, signaling a significantly larger production target than the display industry had previously anticipated, ET News reports. In the now-seemingly deleted report, ET News claimed that Samsung plans to mass-produce 11 million inward-folding OLED displays for Apple next year, as well as 11 million...
AirTag 2 Mock Feature

Apple AirTag 2: Four New Features Found in iOS 26 Code

Thursday December 11, 2025 10:31 am PST by
The AirTag 2 will include a handful of new features that will improve tracking capabilities, according to a new report from Macworld. The site says that it was able to access an internal build of iOS 26, which includes references to multiple unreleased products. Here's what's supposedly coming: An improved pairing process, though no details were provided. AirTag pairing is already...
iOS 26

Apple Releases iOS 26.2 With Alarms for Reminders, Lock Screen Changes, Enhanced Safety Alerts and More

Friday December 12, 2025 10:10 am PST by
Apple today released iOS 26.2, the second major update to the iOS 26 operating system that came out in September, iOS 26.2 comes a little over a month after iOS 26.1 launched. ‌iOS 26‌.2 is compatible with the ‌iPhone‌ 11 series and later, as well as the second-generation ‌iPhone‌ SE. The new software can be downloaded on eligible iPhones over-the-air by going to Settings >...
iOS 26

15 New Things Your iPhone Can Do in iOS 26.2

Friday December 5, 2025 9:40 am PST by
Apple is about to release iOS 26.2, the second major point update for iPhones since iOS 26 was rolled out in September, and there are at least 15 notable changes and improvements worth checking out. We've rounded them up below. Apple is expected to roll out iOS 26.2 to compatible devices sometime between December 8 and December 16. When the update drops, you can check Apple's servers for the ...
maxresdefault

iOS 26 Code Leak Reveals Apple Smart Home Hub Details

Thursday December 11, 2025 4:02 pm PST by
Apple is working on a smart home hub that will rely heavily on the more capable version of Siri that's coming next year. We've heard quite a bit about the hub over the last two years, but a recent iOS 26 code leak provides additional insight into what we can expect and confirms rumored features. Subscribe to the MacRumors YouTube channel for more videos. Macworld claims to have access to an ...

Top Rated Comments

flyinmac Avatar
99 months ago
Hmm.... security protocol creates a vulnerability. To protect yourself, stop encrypting your emails???

Interesting.
Score: 12 Votes (Like | Disagree)
arekm Avatar
99 months ago
This looks like another clickbait by (almost pseudo) research teams. The problem is within mail software and not PGP encryption standard or tools.

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html
Score: 7 Votes (Like | Disagree)
rodpascoe Avatar
99 months ago
Oh the irony.
Score: 6 Votes (Like | Disagree)
flyinmac Avatar
99 months ago
Hope the alert was not sent by email LOL
Going back to using birds to deliver my messages. Considered pigeons... but I want a bird that can shred anyone who tries to intercept my message. Decided on Hawks.
Score: 4 Votes (Like | Disagree)
Detektiv-Pinky Avatar
99 months ago

<snip>
From what I've read, it's a bug in PGP, not mail
I heard differently. It is supposedly a bug affecting any kind of Email encryption using MIME and automatically loading remote content. Also the in-build S/MIME encryption is at risk.
Score: 3 Votes (Like | Disagree)
belvdr Avatar
99 months ago
From what I've read, it's a bug in PGP, not mail
It's a problem in the mail user agent (MUA), not PGP/GPG. From the mailing list:

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html


The topic of that paper is that HTML is used as a back channel to create an oracle for modified encrypted mails. It is long known that HTML mails and in particular external links like <img href="tla.org/TAG"/> are evil if the MUA actually honors them (which many meanwhile seem to do again; see all these newsletters). Due to broken MIME parsers a bunch of MUAs seem to concatenate decrypted HTML mime parts which makes it easy to plant such HTML snippets.

There are two ways to mitigate this attack

- Don't use HTML mails. Or if you really need to read them use a
proper MIME parser and disallow any access to external links.

- Use authenticated encryption.
It also appears that some versions of OpenPGP already use authenticated encryption. From what I'm reading, this is a really old bug that many wanted to get fixed, but the MUAs fail to fix it.
Score: 3 Votes (Like | Disagree)