Claude Code CVE-2026-39861:sandbox escape via symlink

(github.com)

49 points | by Armor1AI 2 days ago ago

9 comments

  • bredren a day ago ago

    I identified this in August last year but it was specifically excluded by Anthropic's Vulnerability Disclosure Program Policy at the time.

    You can still see the exclusion on HackerOne: https://hackerone.com/anthropic-vdp/policy_scopes

       Out of Scope:
    
        Abusing intended functionality of Claude CLI
        Using aliased commands, symlinks or other environment-specific settings to bypass permission prompts
        Local storage of Claude Code credentials, configuration and logs
    
    Symlinks have been very important to manage skills from disparate sources and managing multiple CLIs.

    Codex did not originally support symlink'd skills but added it in response to user requests on Jan 9th.

  • Imustaskforhelp 2 days ago ago

    Interesting that the submission just before this is about:

    Anthropic response to 1-click pwn: Shouldn't have clicked 'ok': https://news.ycombinator.com/item?id=48057836

    This makes me think a bit more about this CVE more too.

    Anthropic lately has been really trying to burn any/every good will that they have it seems. Also a bit ironical about how the most dangerous model (Mythos) which can find CVE in other projects wasn't able to find this CVE within the claude-code project itself.

  • az226 a day ago ago

    And yet Mythos couldn’t find it. Whomp whomp

    • amluto a day ago ago

      Mythos might be good at finding holes in an actual defined security boundary. But trying to audit Claude Code would be like trying to find the holes in Swiss cheese. Of course they’re there!

      • stuaxo 10 hours ago ago

        Oh is THIS the real reason they haven't released it?

        It's the first thing people will point mythos at.

        • amluto 3 hours ago ago

          I’m fairly confident that almost any decent LLM trained on agentic command line workflows could break out of Claude Code. It’s really not hard.

    • quinncom a day ago ago

      Probably it did, but just thought, “I’m saving this one just for me”

    • perching_aix a day ago ago

      I honestly wonder if they run it against it. Like sure, it'd be very, very obvious for them to. But it'd be so quintessentially human not to.

      The shoemaker's children go barefoot and all...

    • philipwhiuk a day ago ago

      Maybe if they'd submitted each file twice instead of only once /s