dbcve.org
Race ConditionWeakness · CWE-362

CVE-2026-31827

HIGH · 7.1 CVSS v4.0 Published 2026-03-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
77/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Alienbin is an anonymous code and text sharing web service. In 1.0.0 and earlier, the /save endpoint in server.js drops and recreates the MongoDB TTL index on the entire post collection for every new paste submission. When User B submits a paste with a short TTL (e.g., 30 seconds), the TTL index is recreated with expireAfterSeconds: 30 for all documents in the collection. This causes User A's paste (originally set to 7 days) to be deleted after 30 seconds. An attacker can intentionally delete all existing pastes by repeatedly submitting pastes with ttlOption=30s.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The /save endpoint in Alienbin 1.0.0 and earlier drops and recreates the MongoDB TTL index on the entire post collection for every new paste submission. When User B submits a paste with a short TTL (e.g., 30 seconds), the TTL index is recreated with expireAfterSeconds: 30 for ALL documents, causing User A's paste (originally set to 7 days) to be prematurely deleted.

MitigationCreate the TTL index once at application startup rather than on every save, or implement a per-document expiration mechanism using a separate cleanup process instead of relying on MongoDB's TTL index recreation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Alienbin installation and version
    Check the installed Alienbin version by inspecting the application binary, package.json, or running 'alienbin --version' if a CLI is available. Compare against the affected range: 1.0.0 and earlier.
    Affected if Alienbin version is 1.0.0 or earlier
  2. Verify MongoDB TTL index on post collection
    Connect to the MongoDB instance and run: db.posts.getIndexes() to list all indexes on the posts collection. Identify if any index has the 'expireAfterSeconds' field present (indicating a TTL index).
    Affected if A TTL index exists on the posts collection with any expireAfterSeconds value
  3. Confirm the /save endpoint exists
    Check if the application exposes a /save HTTP endpoint by reviewing the application routes, API documentation, or by making a POST request to /save (if the application is accessible).
    Affected if The /save endpoint is present and accessible
  4. Test TTL index recreation behavior
    Submit two test pastes with significantly different TTL values (e.g., one with 30 seconds, one with 7 days) through the /save endpoint. After each submission, query the TTL index configuration again using db.posts.getIndexes() and observe if expireAfterSeconds changes.
    Affected if The expireAfterSeconds value changes after each new paste submission, overwriting the previous TTL setting

If Alienbin 1.0.0 or earlier is running with a MongoDB TTL index on the posts collection and the /save endpoint recreates that index on each submission, the environment is affected by this vulnerability where pastes may be prematurely deleted.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Create the TTL index once at application startup rather than on every save, or implement a per-document expiration mechanism using a separate cleanup process instead of relying on MongoDB's TTL index recreation.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-31827 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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