CVE-2026-57957Public exploitNetwork attack vector

Credentialed cross-origin file upload via Origin reflection

Published Jun 29, 2026 · Updated Jun 29, 2026

CORS misconfiguration in Papermark 0.22.0 and earlier allows remote attackers to upload files through an authenticated viewer session. The TUS viewer handler at pages/api/file/tus-viewer/[[...file]].ts reflects any Origin while allowing credentials, so browsers attach session cookies. Exploitation requires a victim with an active dataroom session to visit attacker-controlled content, enabling unauthorized file injection and response reading.

CVSS severity2.3
Low
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CORS misconfiguration in Papermark 0.22.0 and earlier allows remote attackers to upload files through an authenticated viewer session. The TUS viewer handler at pages/api/file/tus-viewer/[[...file]].ts reflects any Origin while allowing credentials, so browsers attach session cookies. Exploitation requires a victim with an active dataroom session to visit attacker-controlled content, enabling unauthorized file injection and response reading.

The record

CVE
CVE-2026-57957
Published
Jun 29, 2026
Updated
Jun 29, 2026
Vendor
Papermark
Product
Papermark
Classifications
CWE-942, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=0.22.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Papermark · Papermarkversion=0 <=0.22.0

Published CVSS scores

2.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
4.7VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-942Permissive Cross-domain Security Policy with Untrusted Domains
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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