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The vulnerability exists in the API key validation mechanism of OctoPrint. The system uses a standard string comparison that checks provided API keys against the stored secret character-by-character. This comparison operation “short-circuits,” meaning it stops processing as soon as it encounters the first mismatched character. Consequently, a request with a correct first character takes microscopically longer to process than one with an incorrect first character, as it proceeds to compare the second character before failing. By making vast numbers of authentication attempts with different candidate keys and precisely measuring the response times of the denial messages, an attacker can statistically analyze these timing differences. This allows for the incremental derivation of the secret API key, one character at a time, over the network. The attack is complex and requires a stable, low-latency connection to the target with minimal noise to detect the subtle timing variations introduced by the flawed comparison logic.
DailyCVE Form:
Platform: OctoPrint
Version: <= 1.11.5
Vulnerability: Timing Attack
Severity: Critical
Date:
Prediction: Patch 1.11.6
What Undercode Say:
Analytics:
Simulating timing measurement for a single request
curl -o /dev/null -s -w 'Response Time: %{time_total}\n' -H "X-Api-Key: guess1" http://octoprint.local/api/version
Example of vulnerable short-circuit comparison (conceptual) def validate_key(provided, stored): for i in range(len(provided)): if provided[bash] != stored[bash]: Fails on first mismatch return False return True
How Exploit:
1. Enumerate characters positionally.
2. Send repeated auth requests.
3. Measure response times.
4. Statistical analysis timing.
5. Derive full key.
Protection from this CVE:
1. Update to 1.11.6.
2. Use constant-time comparison.
3. Implement network segmentation.
4. Avoid public internet exposure.
Impact:
API key compromise.
Unauthorized access.
Remote control printer.
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Sources:
Reported By: github.com
Extra Source Hub:
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