danmu_api: Authentication bypass via default token in env endpoints
Summary
danmu_api before 1.21.7 allows unauthenticated remote attackers to change the server environment configuration when the default TOKEN is in use and ADMIN_TOKEN is not set. By sending POST requests to /api/env/set, /api/env/add or /api/env/del, an attacker can set ADMIN_TOKEN and lock out operators, redirect OTHER_SERVER or PROXY_URL for server-side request forgery, and trigger a redeployment. The vulnerable state is the shipped default configuration.
Affected
- huangxd- danmu_api versions before 1.21.7 (affected range 0 to below 1.21.7)
- Vulnerable when the default TOKEN is used and ADMIN_TOKEN is unset
Fixed in
- Upgrade to danmu_api 1.21.7 or later (fix commit 6e93478)
Workaround
- Change the default TOKEN and set a strong ADMIN_TOKEN (not vendor-confirmed)
- Restrict network access to the service (VPN or internal network only)
- Do not expose the service to the internet until it is patched
Exploitation
- Not marked as known exploited; not listed in CISA KEV in the sources checked
- Public detection template exists (Nuclei); no public exploit confirmed
- In-the-wild exploitation unconfirmed
Our recommendation
- Inventory all danmu_api deployments (Docker, Vercel, Cloudflare, NAS, VPS)
- Upgrade to 1.21.7 or later as a priority
- Rotate secrets stored in the environment, as they may have been read or changed
- Remove direct internet exposure and check logs for requests to /api/env/*
- Note: CVSS scores differ between sources; the CNA score 9.3 (CVSS 4.0) is used here
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- VulnCheck advisory www.vulncheck.com
- GitHub issue #531 github.com
- Fix commit 6e93478 github.com
- Vulnerable source (worker.js) github.com
- Project repository github.com
- Nuclei detection template PR github.com
- VulDB entry vuldb.com
- OffSeq threat radar radar.offseq.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 00:43.
Original description (NVD)
danmu_api before 1.21.7 contains an authentication bypass vulnerability that allows unauthenticated attackers to modify server environment configuration when the default TOKEN is used and ADMIN_TOKEN is unset. Attackers can send POST requests to /api/env/set, /api/env/add, or /api/env/del to set ADMIN_TOKEN, lock out operators, redirect OTHER_SERVER or PROXY_URL for SSRF, and trigger redeployment.
NVD references (5)
- https://github.com/huangxd-/danmu_api
- https://github.com/huangxd-/danmu_api/blob/5ef63a01bae7c4bad4dcd7bafbbcdcf33aa82564/danmu_api/worker.js#L223-…
- https://github.com/huangxd-/danmu_api/commit/6e93478064a0ce4e7ed3bc2eae88adaad1b7ab02
- https://github.com/huangxd-/danmu_api/issues/531
- https://www.vulncheck.com/advisories/danmu-api-before-1.21.7-authentication-bypass-via-default-token-in-env-e…
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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