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

Apple Shopping Event 2025

Apple Announces 2025 Black Friday Event, Here's What You Can Get

Thursday November 20, 2025 6:28 am PST by
Apple's annual four-day Black Friday through Cyber Monday shopping event is returning on Friday, November 28 through Monday, December 1 in many countries, including the United States, Canada, Australia, New Zealand, France, Germany, Italy, Spain, the United Kingdom, Belgium, the Netherlands, Sweden, Thailand, and others. During the shopping event, customers can get an Apple gift card with...
iPhone 17 Pro Cosmic Orange

10 Reasons to Wait for Next Year's iPhone 18 Pro

Wednesday November 19, 2025 4:00 am PST by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
iOS 26

Everything New in iOS 26.2 Beta 3

Monday November 17, 2025 3:20 pm PST by
Apple provided developers with the third beta of an upcoming iOS 26.2 update, and there are still new features that are being added with each beta that we get. We've rounded up all of the changes that Apple made in beta 3. AirDrop Apple added new AirDrop functionality, providing a way for two people to share files temporarily without having to add one another as contacts. iOS 26.2...
applecare apple care banner

Apple Brings New AppleCare+ Options to India

Tuesday November 18, 2025 8:42 am PST by
Apple today announced an expansion of AppleCare+ coverage in India, with new options for monthly and annual plans, and the addition of Theft and Loss for iPhone for the first time. Options for monthly and annual AppleCare+ plans in India provide more choice and flexibility, allowing users to keep coverage for as long as they require. Apple's vice president of Worldwide iPhone Product...
iOS 26

iOS 26.2 Adds These New Features to Your iPhone

Thursday November 20, 2025 10:50 am PST by
iOS 26.2 is currently in beta testing. The upcoming update includes a handful of new features and changes on the iPhone, including a new Liquid Glass slider for the Lock Screen's clock, offline lyrics for Apple Music, and more. In a recent press release, Apple confirmed that iOS 26.2 will be released to all users in December, but it did not provide a specific release date. Keep reading...
ipad mini 7 feature red and blue

iPad Mini 8: Four Major New Features to Expect

Wednesday November 19, 2025 7:50 am PST by
Apple's eighth-generation iPad mini is highly likely to arrive next year, offering a significant refresh of the device with at least four major new features. OLED Display The next-generation version of the iPad mini could feature an OLED display, as part of Apple's plan to expand the display technology across many more of its devices. Apple's first OLED device was the Apple Watch in 2015, ...
hikawa phone grip stand apple%402x

Apple Launches Second Limited-Edition iPhone Accessory in a Month

Friday November 21, 2025 3:53 am PST by
Apple has begun selling the Hikawa Phone Grip and Stand, a new limited-edition iPhone accessory designed with accessibility in mind. Designed by LA-based Bailey Hikawa to celebrate the 40th anniversary of accessibility at Apple, the grip uses magnets to securely snap onto any iPhone with MagSafe. Apple says it can be removed with ease, and doubles as a stand with two different viewing...
iPhone 17 Pro and Air N1 Feature

iPhone 17 vs. iPhone 16 Wi-Fi Speeds: New Study Reveals the Winner

Tuesday November 18, 2025 10:53 am PST by
A new study has revealed that the iPhone 17, iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air achieve significantly faster average Wi-Fi speeds compared to the iPhone 16 series, thanks to Apple's custom-designed N1 chip. The study was conducted by Ookla, the company behind the popular Speedtest website and app. It said the results are based on global, crowdsourced Speedtest user data...
macbook black friday

The Best Early Black Friday Mac Deals

Tuesday November 18, 2025 7:32 am PST by
We're getting closer to Black Friday, which lands next week on Friday, November 28. In the lead-up to the shopping holiday, we're tracking a few lowest-ever prices on Apple's most popular Macs, including the M4 MacBook Air and brand new M5 MacBook Pro. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment,...
Apple Wallet ID Illinois

iPhone Driver's License Feature Launching in Illinois

Tuesday November 18, 2025 8:47 am PST by
In select U.S. states, residents can add their driver's license or state ID to the Wallet app on the iPhone and Apple Watch, providing a convenient and contactless way to display proof of identity or age at select airports and businesses, and in select apps. Starting this Wednesday, November 19, the feature will be available to residents of Illinois. The announcement confirmed that the...

Top Rated Comments

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

Interesting.
Score: 12 Votes (Like | Disagree)
arekm Avatar
98 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
98 months ago
Oh the irony.
Score: 6 Votes (Like | Disagree)
flyinmac Avatar
98 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
98 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
98 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)