Quick answers
- Is CVE-2026-80431 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-80431 being exploited in the wild.
- How severe is CVE-2026-80431?
- Informational severity, published 25 September 2026.
- Which products and versions are affected?
- Kovidgoyal Kitty 0.40.0 before 0.49.0.
- Is there a fix for CVE-2026-80431?
- A patch was published on 2026-09-21: Fixed in version 0.49.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-80431 attacked?
- It is attacked over the network or with local access, in a network appliance.
- Am I affected by CVE-2026-80431?
- Check whether you run Kovidgoyal Kitty at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An out-of-bounds write vulnerability exists in the natural width branch of kitty's text sizing protocol (OSC 66 escape code handling). The screen_handle_multicell_command() function in kitty/screen.c appends grapheme cluster codepoints without bounds checking to a fixed four-element array on the stack; a cluster longer than four codepoints overflows the buffer. If a flush occurs first, the buffer migrates to the heap, but the write still exceeds the heap allocation. Exploitation requires writing specially crafted escape codes to the terminal.
Affected products
- kovidgoyal kitty 0.40.0 before 0.49.0
Timeline
- 2026-09-25: disclosed
- 2026-09-21: patched: Fixed in version 0.49.0