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Fencer Intel
medium 4.4

CVE-2026-121549 json

nnn through 5.3 Insecure Temporary File Symlink Overwrite via pdfread and nuke Plugins

published 6d ago modified 2d ago also EUVD-2026-115894

cvss
4.4
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 1%
public exploits
0
none known

Summary

nnn through 5.3 contains an insecure temporary file vulnerability in the pdfread and nuke plugins that allows local attackers to overwrite files by exploiting predictable paths in /tmp. Attackers can pre-create a symlink at the name-derived or PID-derived path so the victim's plugin truncates and overwrites any file the victim can write.

Patch / fix

Is CVE-2026-121549 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-121549 updated cvss 4.4

nnn: nnn: Arbitrary file overwrite via insecure temporary file creation in plugins

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

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

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/jarun/nnn/issues/2188 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 4.1 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 3.1 4.4 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
CNA 4.0 4.1 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • jarun nnn

Classification

Weakness
  • CWE-377 DEPRECATED: Insecure Temporary File

References

Sources

Fencer Intel 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.