CVE-2026-55086Public exploit

File overwrite via predictable symlink-following temp paths

Published Aug 19, 2026 · Updated Aug 25, 2026

Insecure temporary-file handling in Etherpad before 3.1.0 allows local users to overwrite files writable by the Etherpad process. ImportHandler.ts and ExportHandler.ts derive shared temporary paths from predictable Math.random() values and then follow precreated symbolic links during writes, renames, or conversion output. Exploitation requires a local unprivileged account, a shared world-writable temporary directory, and a correctly predicted name; writes are limited to targets accessible to the service account.

CVSS severity4.2
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure temporary-file handling in Etherpad before 3.1.0 allows local users to overwrite files writable by the Etherpad process. ImportHandler.ts and ExportHandler.ts derive shared temporary paths from predictable Math.random() values and then follow precreated symbolic links during writes, renames, or conversion output. Exploitation requires a local unprivileged account, a shared world-writable temporary directory, and a correctly predicted name; writes are limited to targets accessible to the service account.

The record

CVE
CVE-2026-55086
Published
Aug 19, 2026
Updated
Aug 25, 2026
Vendor
Etherpad Foundation
Product
Etherpad
Classifications
CWE-377, CWE-59, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=< 3.1.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Etherpad Foundation · Etherpadversion=< 3.1.0

Published CVSS scores

4.2GitHubCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-377Insecure Temporary File
CWE-59Improper Link Resolution Before File Access ('Link Following')
T1068Exploitation for Privilege Escalation

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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