# CVE-2026-31827: Alienbin: TTL Index Race Condition allows unauthorized deletion of other users data

> An attacker can delete other users' pastes by exploiting a race condition in the TTL index recreation logic during paste submission.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Mar 2026
- **Updated:** 11 Mar 2026

## What is CVE-2026-31827?

CVE-2026-31827 is a high-severity vulnerability in Blue-B Alienbin, published on 10 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-31827?


## How do I fix CVE-2026-31827?

No fix has been published for CVE-2026-31827 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-31827 being exploited?

There is no known exploitation of CVE-2026-31827 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31827 and fix it if it is affected.

What it is: CVE-2026-31827 is a high-severity vulnerability in Blue-B Alienbin, published on 10 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-31827 in the wild and no public exploit code.

Affected product: Blue-B Alienbin. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-31827/ (Markdown: https://insights.sbomify.com/CVE-2026-31827/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31827
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31827
- OSV: https://osv.dev/vulnerability/CVE-2026-31827

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31827/
Summaries are generated and may contain mistakes; the official description above is the record.