CVE-2026-61740: LightRAG is Vulnerable to Authentication Bypass: hardcoded DEFAULT_TOKEN_SECRET and public /auth-status defeat LIGHTRAG_API_KEY protection

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.7%, percentile 51: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 51% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes lightrag-hku (PyPI) < 1.5.4, fixed in 1.5.4. Check your lockfile, including transitive dependencies.

What it is

LightRAG provides simple and fast retrieval-augmented generation. Prior to 1.5.4, when LightRAG is deployed with LIGHTRAGAPIKEY set but AUTHACCOUNTS unset, X-API-Key protection can be bypassed because lightrag/api/auth.py falls back to a hardcoded DEFAULTTOKENSECRET, /auth-status and /login can mint guest JWTs, and combineddependency in lightrag/api/utilsapi.py accepts a valid guest token before checking the API key. A remote unauthenticated attacker can call endpoints guarded by combinedauth, including document read, upload, deletion, graph mutation, and query endpoints. This vulnerability is fixed in 1.5.4.

From the GitHub advisory

Summary

When LightRAG is deployed with LIGHTRAGAPIKEY set but AUTHACCOUNTS unset (an officially documented "API-Key authentication" mode), the X-API-Key protection can be bypassed by any remote unauthenticated attacker. The bypass does not require network contact with the victim server — an attacker can mint a valid guest JWT offline using the hardcoded DEFAULTTOKENSECRET committed in the repository and then call any endpoint guarded by Depends(combinedauth), including destructive operations such as DELETE /documents, POST /documents/upload, /documents/clearcache, and POST /query.

This is distinct from the previously-fixed GHSA-mcww-4hxq-hfr3 / CVE-2026-30762, which only covered the AUTHACCOUNTS-configured case. The API-Key-only deployment profile is still fully exploitable on current main (commit 157c331, v1.4.15).

Root cause

Three independent issues combine:

Weakness type: CWE-287, CWE-798.

Product: lightrag-hku (PyPI) · Assigned by: GitHub_M · Published: 2026-07-15

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.66% probability of exploitation activity in the next 30 days; percentile 51.

Timeline

• 2026-07-15 — CVE record last updated
• 2026-07-15 — CVE record published by GitHub_M
• 2026-07-20 — GitHub-reviewed advisory GHSA-f4vv-55c2-5789 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-f4vv-55c2-5789 github.com
2. CVE.org record CVE-2026-61740 cve.org
3. NVD entry CVE-2026-61740 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical PyPI advisories · Today’s Security Digest