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Fencer Intel
critical 9.3

CVE-2026-77621 json

Vector: Arbitrary file write in the file sink via templated path (path traversal).

published 3mo ago modified last mo. also EUVD-2026-84510 , GHSA-6342-xwvw-c637

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository vectordotdev/vector. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

Vector is a high-performance observability data pipeline. From 0.10.0 until 0.57.0, the file sink renders its templated path from event fields and opens the result without confining it to an intended directory. When an untrusted source supplies an event field used by the path template, the value can contain an absolute path or parent-directory traversal, causing Vector to create parent directories and create or overwrite files outside the intended location with the Vector process privileges. The resulting file write can modify sensitive files and can lead to code execution when a scheduled task, authorization file, or subsequently executed script is targeted. This issue is fixed in version 0.57.0.

Patch / fix

Is CVE-2026-77621 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.

Check with Fencer

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-2026-77621 updated cvss 8.1

vector: Vector: Arbitrary file write in the file sink via templated path (path traversal).

  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9
    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
none
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

1.12% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:H
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:H/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

  • vectordotdev vector

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-73 External Control of File Name or Path

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.

The maintainers of vectordotdev/vector published their own advisory on GitHub. Reviewed sources take precedence over it.