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

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

by

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.

Tags: Encryption, Security

Popular Stories

General Discord Feature

Discord Voice and Video Calls Now End-to-End Encrypted by Default

Wednesday May 20, 2026 4:43 am PDT by
Discord says it has switched on end-to-end encryption (E2EE) by default for every voice and video call across its platforms, including desktop, mobile, web, and consoles like PlayStation and Xbox. The rollout covers DMs, group DMs, voice channels, and Go Live streams. There's no opt-in required, or any setting to change. Stage channels are the only exception, given that they're built for...
Read Full Article • 18 comments
Apple Lists 250 Changes Across iOS 27 and More Feature

Apple Shares List of 250 Changes Across iOS 27, macOS Golden Gate, and More

Wednesday June 10, 2026 1:34 pm PDT by
During its WWDC 2026 keynote on Monday, Apple briefly showed a slide with hundreds of new features and enhancements coming across iOS 27, macOS 27 Golden Gate, watchOS 27, tvOS 27, and visionOS 27. All of the software updates are currently available as developer betas, and they are expected to be released to all users in September. We already highlighted some of the key new features from the ...
Read Full Article • 132 comments
Apple Event Logo

Apple to Release These 15 New Products Later This Year

Friday June 12, 2026 7:45 am PDT by
Apple's annual WWDC developers conference is drawing to a close, but there is still a lot to look forward to in the second half of the year. Apple is expected to release at least 15 more products later this year. Now that the more intelligent and personal version of Siri has finally arrived in beta, a full two years after Apple first previewed it at WWDC 2024, we should begin to see some new ...
Read Full Article • 35 comments

Top Rated Comments

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

Interesting.
Score: 12 Votes (Like | Disagree)
A
arekm
106 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
rodpascoe
106 months ago
Oh the irony.
Score: 6 Votes (Like | Disagree)
flyinmac Avatar
flyinmac
106 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)
belvdr Avatar
belvdr
106 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)
Detektiv-Pinky Avatar
Detektiv-Pinky
106 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)
Read All Comments