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Fencer Vulns
medium 4.2

CVE-2026-55086 json

Etherpad: Import/export use Math.random() for temp file paths; predictable paths on shared /tmp enable symlink-based file overwrite

published 2026-08-13 2 mo ago modified 2026-09-09 1 mo ago also GHSA-2jwf-f4xq-f24h , EUVD-2026-62741

cvss
4.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

Etherpad is a real-time collaborative editor. Prior to 3.1.0, src/node/handler/ImportHandler.ts and src/node/handler/ExportHandler.ts derive temporary filenames from Math.random() and place them in os.tmpdir(). On a host with a shared world-writable temporary directory, a local unprivileged attacker who predicts a filename can precreate a symbolic link to a file writable by the Etherpad process. Subsequent import or export operations can follow the link through fs.writeFile, fs.rename, or document-conversion output and overwrite the target with partially attacker-controlled content. This issue is fixed in version 3.1.0.

Patch / fix

  • npm ep_etherpad-lite 3.1.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ether/etherpad/security/advisories/GHSA-2jwf-f4xq-f24h referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.2 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N
GitHub 3.1 4.2 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm ep_etherpad-lite
<3.1.0
3.1.0

Affected products

  • ether etherpad

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access
  • CWE-377 DEPRECATED: Insecure Temporary File

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.