CVE-2026-34978Public exploitNetwork attack vector

Unauthenticated file overwrite via unnormalized RSS path

Published Apr 3, 2026 · Updated Apr 3, 2026

Path traversal in the RSS notifier in OpenPrinting CUPS 2.4.16 and earlier allows remote attackers to overwrite lp-writable files. The notifier appends an unnormalized URI resource to CacheDir/rss, writes RSS XML through a temporary file, and renames it over the resolved target. An unauthenticated IPP client that can reach cupsd can traverse into the group-writable CacheDir, replace job.cache, and cause queued jobs to disappear after a scheduler restart.

CVSS severity6.5
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in the RSS notifier in OpenPrinting CUPS 2.4.16 and earlier allows remote attackers to overwrite lp-writable files. The notifier appends an unnormalized URI resource to CacheDir/rss, writes RSS XML through a temporary file, and renames it over the resolved target. An unauthenticated IPP client that can reach cupsd can traverse into the group-writable CacheDir, replace job.cache, and cause queued jobs to disappear after a scheduler restart.

The record

CVE
CVE-2026-34978
Published
Apr 3, 2026
Updated
Apr 3, 2026
Vendor
OpenPrinting
Product
CUPS
Classifications
CWE-22, T1190, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 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=<= 2.4.16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenPrinting · CUPSversion=<= 2.4.16

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

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-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application
T1565.001Stored Data Manipulation

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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