Vulnerability · Published Jun 29, 2026 · Assigned by VulnCheck

CVE-2026-57957Papermark 0.22.0 - CORS Misconfiguration in Viewer Upload Endpoint

Medium 4.7

In plain English

A medium-severity security flaw in papermark from papermark. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities).

Severity (CVSS 3.1)4.7Medium

Exploit odds (30 days)0.4%top 62.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Papermark through 0.22.0 contains a cross-origin resource sharing (CORS) misconfiguration vulnerability that allows unauthenticated remote attackers to perform credentialed cross-origin requests by exploiting the TUS-based viewer upload endpoint reflecting arbitrary request Origins with Access-Control-Allow-Credentials set to true. Attackers can lure authenticated victims to malicious pages that silently issue credentialed cross-origin requests to upload arbitrary files into victim datarooms and read credentialed responses.

Affected products (as reported)

Vendor	Product	Versions
papermark	papermark	0 – through 0.22.0

Weakness: CWE-942 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

References

Researcher Disclosure issue-tracking
Findings Summary issue-tracking
https://www.vulncheck.com/advisories/papermark-cors-misconfiguration-in-viewer-upload-endpoint third-party-advisory