CVE-2025-66556: Nextcloud talk allows participants to blindly delete poll drafts of other users by ID

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• nextcloud talk20.0.0 and later · before 20.1.8
• nextcloud talk21.0.0 and later · before 21.1.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

• nextcloud security-advisories

  • < 20.1.8, >= 21.0.0-beta.1, < 21.1.2affected

Other highest-scoring records for the same primary product.

• CVE-2020-8180A too lax check in Nextcloud Talk 6.0.4, 7.0.2 and 8.0.7 allowed a code injection when a not correctly sanitized talk command was added by a
  40Plan
• CVE-2023-39957Path traversal allows tricking the Talk Android app into writing files into it's root directory
  31Monitor
• CVE-2021-32689Nextcloud Talk not properly disassociating users from chats after account deletion
  26Monitor

Published before and after this one in the same product

• ← EarlierCVE-2023-28845Mar 31, 2023 · Chat room membership disclosed via autocompletion in Nextcloud talk
  14Monitor
• ← EarlierCVE-2023-30540Apr 17, 2023 · Chat poll data can still be queried from API after purging history in Nextcloud talk
  17Monitor
• ← EarlierCVE-2023-45149Oct 16, 2023 · Password of talk conversations can be bruteforced in Nextcloud
  17Monitor

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1const invoice = await Invoice.findById(req.params.id);2res.json(invoice);

1const invoice = await Invoice.findOne({2  id: req.params.id,3  ownerId: req.user.id,4});5if (!invoice) return res.sendStatus(404);6res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.