CVE-2026-23892: OctoPrint has Timing Side-Channel Vulnerability in API Key Authentication
Impact
OctoPrint versions up to and including 1.11.5 are affected by a (theoretical) timing attack vulnerability that allows API key extraction over the network.
Due to using character based comparison that short-circuits on the first mismatched character during API key validation, rather than a cryptographical method with static runtime regardless of the point of mismatch, an attacker with network based access to an affected OctoPrint could extract API keys valid on the instance by measuring the response times of the denied access responses and guess an API key character by character.
Patches
The vulnerability will be patched in version 1.11.6.
Workaround
The likelihood of this attack actually working is highly dependent on the network's latency, noise and similar parameters. An actual proof of concept was not achieved so far. Still, as always administrators are advised to not expose their OctoPrint instance on hostile networks, especially not on the public Internet!
Credits
This vulnerability was discovered and responsibly disclosed to OctoPrint by Knox Liu.
Other sources
OctoPrint provides a web interface for controlling consumer 3D printers. OctoPrint versions up to and including 1.11.5 are affected by a (theoretical) timing attack vulnerability that allows API key extraction over the network. Due to using character based comparison that short-circuits on the first mismatched character during API key validation, rather than a cryptographical method with static runtime regardless of the point of mismatch, an attacker with network based access to an affected OctoPrint could extract API keys valid on the instance by measuring the response times of the denied access responses and guess an API key character by character. The vulnerability is patched in version 1.11.6. The likelihood of this attack actually working is highly dependent on the network's latency, noise and similar parameters. An actual proof of concept was not achieved so far. Still, as always administrators are advised to not expose their OctoPrint instance on hostile networks, especially not on the public Internet.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23892?
CVE-2026-23892 is categorized as a theoretical timing attack vulnerability that affects OctoPrint versions up to 1.11.5.
How do I fix CVE-2026-23892?
To fix CVE-2026-23892, upgrade OctoPrint to version 1.11.6 or later.
What is the impact of CVE-2026-23892?
CVE-2026-23892 allows for potential API key extraction over the network due to a timing side-channel vulnerability.
Which versions of OctoPrint are affected by CVE-2026-23892?
OctoPrint versions up to and including 1.11.5 are affected by CVE-2026-23892.
What type of vulnerability is CVE-2026-23892?
CVE-2026-23892 is classified as a timing side-channel vulnerability related to API key authentication.