1983289 - reddit blocking access to threads with error about "blocked by network security"

Status: VERIFIED FIXED

(Web Compatibility :: Site Reports, defect)

Description

[Randell Jesup [:jesup] (needinfo me)]

https://webcompat.com/issues/171923
https://www.reddit.com/r/firefox/comments/1mqmsv5/your_request_has_been_blocked_by_network_security/

If you browse to https://www.reddit.com/r/firefox/comments/1mqmsv5/your_request_has_been_blocked_by_network_security/ in a private window, you'll get a red warning banner: "Your request has been blocked by network security. Please try to login with your Reddit account."

Note that logging in doesn't change this.

From a non-PB window, in a new profile, you (likely) will get the same message. An existing profile logged into reddit (usually) won't get it.

Switching to old.reddit.com makes it go away.

Comment 1

[Rob Wu [:robwu]]

I suspect that preload may be related.

The body contains this (edit: original body contains preload):

<link rel="preload" href="/svc/shreddit/comments/r/firefox/t3_1mqmsv5?render-mode=partial&amp;seeker-session=true" as="fetch" /> <link rel="preload" href="/svc/shreddit/pdp-right-rail/related/firefox/t3_1mqmsv5?render-mode=partial&amp;seeker-session=true" as="fetch" />

If I create an extension that does str = str.replaceAll(/<link rel="preload" href="/g, "$&https://example.com/");, then the content loads fine.

If I drop the preload tag, str = str.replaceAll("preload", "perload");, then some error in Reddit happens and the page does not load (but there is no red banner either).

Comment 2

[Rob Wu [:robwu]]

Attachment: reddit-body-mod.zip

This extension fixes Reddit for me. See background.js

(Visit about:debugging to load it)

Comment 3

[Randell Jesup [:jesup] (needinfo me)]

Note that if I navigate to a thread in reddit, say from r/firefox, it works. If I take the same URL and paste it into the URLBar, I get the network error every time (testing in Private Browsing window, not logged int)

Comment 4

[Rob Wu [:robwu]]

(In reply to Randell Jesup [:jesup] (needinfo me) from comment #3)

Note that if I navigate to a thread in reddit, say from r/firefox, it works. If I take the same URL and paste it into the URLBar, I get the network error every time (testing in Private Browsing window, not logged int)

The "navigate" by clicking is not a full page navigation, but JavaScript + history.pushState.

Even after navigating, if you then reload the page, the bug re-occurs. I strongly suspect the preload tag in the HTML source of the document, because manually cutting it out (with an extension - comment 1 & comment 2) causes the bug to disappear.

Comment 5

[Rob Wu [:robwu]]

about:logging with the following preset (Network + Fetch + PreloadService):
https://share.firefox.dev/3Jjc52Q

(MOZ_LOG=timestamp,sync,nsHttp:5,cache2:5,nsSocketTransport:5,nsHostResolver:5,EarlyHint:5,Fetch:5,PreloadService:5 )

Comment 6

[Brian Landers]

Just chiming in from the Reddit traffic team to say we're aware of this issue and are actively looking at it from our side.

Comment 7

[Valentin Gosu [:valentin]]

It seems if I set network.http.http2.enabled to false in about:config the problem goes away.
So it seems to be something specific to our H2 implementation.

Comment 8

[Rob Wu [:robwu]]

Reddit also announced that they are working on it at https://www.reddit.com/r/RedditBugs/comments/1mr2w7f/webfirefox_some_firefox_users_are_reporting_a/

[Web/Firefox] Some Firefox users are reporting a "blocked by network security" error

Investigating
Report(s)

• Opening posts in a new tab gets "Your request has been blocked by network security. Please try to login with your Reddit account." (Desktop)

• [Desktop Firefox] Sometimes getting an error when trying to view comments. "Your request has been blocked by Network security. Please log into your account."

• [Firefox] "your request has been blocked by network security try login with your reddit account" error

---

Hey folks - we're aware that some of you are receiving a "blocked by network security" error across some pages on www.reddit.com. Just confirming that we're actively investigating the issue, and I'll post updates here as we get closer to resolving things.

Comment 9

[Rob Wu [:robwu]]

I and another colleague cannot reproduce this issue any more.

Brian, could you confirm that you have rolled out a fix?

Do you also know the cause of the issue, and is this something that Firefox could/should investigate/fix?

Comment 10

[Brian Landers]

Reddit has rolled out a mitigation while we investigate a permanent solution.

I don't think there's any action needed from Firefox on this.

Comment 11

[Valentin Gosu [:valentin]]

Hi Brian,

Thank you for the quick fix.
When possible, we'd appreciate it if you could let us know what caused the problem. I'm curious whether other websites might also be affected by it, and whether Firefox needs to take steps to mitigate such issues.
Thanks!

Comment 12

[Rob Wu [:robwu]]

I'm witnessing the same issue again: Reddit posts cannot be loaded, unless I trigger a navigation from a subreddit to a post. E.g. click on a post in /r/firefox and it loads, reload the page and it fails again with "Your request has been blocked by network security. Please try to login with your Reddit account."

Comment 13

[Rob Wu [:robwu]]

^ The renewed instance of the issue appears to have been resolved.

Comment 14

[Calin Tanase]

Verified, the issue no longer reproduces.

Tested with:

• Browser / Version: Firefox 143.0-candidate build 1
• Operating System: MacOS Sequoia 15.6.1