CVE-2026-31827

Alienbin: TTL Index Race Condition allows unauthorized deletion of other users data

State: Published
Severity: 7.1 High
Published: Mar 10, 2026
Updated: Mar 11, 2026
Reserved: Mar 9, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	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	GitHub_M

Weaknesses

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Affected Products

Product	Versions
AlienbinBlue-B	<= 1.0.0Affected

References

https://github.com/Blue-B/Alienbin/security/advisories/GHSA-hqvr-6v89-gwff

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