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CVE-2026-31431: Copy Fail vs. rootless containers

dragonsreach.it

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Re: CVE-2026-31431: Copy Fail vs. rootless containers

#13
post #8

Sigh. 1. I would hope the default seccomp policy blocks AF_ALG in these containers. I bet it doesn’t. Oh well. 2. The write-to-RO-page-cache primitive STILL WORKED! It’s just that the particular exploit used had no meaningful effect in the already-root-in-a-container context. If you think you are safe, you’re probably wrong. All you need to make a new exploit is an fd representing something that you aren’t supposed t…

In fact, the authors specifically say on the very first line of their website that the copy/fail primitive can be used as a container escape. The entire premise of this article is flawed and irresponsible.

Re: CVE-2026-31431: Copy Fail vs. rootless containers

#18
post #8

Sigh. 1. I would hope the default seccomp policy blocks AF_ALG in these containers. I bet it doesn’t. Oh well. 2. The write-to-RO-page-cache primitive STILL WORKED! It’s just that the particular exploit used had no meaningful effect in the already-root-in-a-container context. If you think you are safe, you’re probably wrong. All you need to make a new exploit is an fd representing something that you aren’t supposed t…

In fact, the authors specifically say on the very first line of their website that the copy/fail primitive can be used as a container escape. The entire premise of this article is flawed and irresponsible.

[deleted]

Re: CVE-2026-31431: Copy Fail vs. rootless containers

#19
post #11

[flagged]

> (like reading env vars and sending them to an external server) it'd not be able to send credentials or fetch a malware remotely at all due to the DNS queries being intercepted by eBPF and being sent to a CoreDNS proxy.

Wouldn’t the exploit then just use ip addresses directly?

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