CVE-2026-34978 | OpenPrinting CUPS: Path traversal in RSS notify-recipient-uri enables file write outside CacheDir/rss (and clobbering of job.cache)

Exp

OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16 and prior, the RSS notifier allows .. path traversal in notify-recipient-uri (e.g., rss:///../job.cache), letting a remote IPP client write RSS XML bytes outside CacheDir/rss (anywhere that is lp-writable). In particular, because CacheDir is group-writable by default (typically root:lp and mode 0770), the notifier (running as lp) can replace root-managed state files via temp-file + rename(). This PoC clobbers CacheDir/job.cache with RSS XML, and after restarting cupsd the scheduler fails to parse the job cache and previously queued jobs disappear. At time of publication, there are no publicly available patches.

Published: 2026-04-03 Last update: 2026-04-16 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34978 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-34978

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-34978

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.06% 0.03% -0.03%
2 2026-04-04 — 0.06% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34978

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 2.5 [email protected]

Weakness enumeration for CVE-2026-34978

OS Trackers for CVE-2026-34978

vendor priority summary link
alpine — CVE-2026-34978: 1 source package rows (cups); 69 state rows across 6 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 0, open 69. https://security.alpinelinux.org/vuln/CVE-2026-34978
debian not yet assigned CVE-2026-34978 not yet assigned priority: Debian including 1 source packages (cups), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-34978
redhat medium — https://access.redhat.com/security/cve/CVE-2026-34978
suse medium — https://www.suse.com/security/cve/CVE-2026-34978/
ubuntu medium CVE-2026-34978 medium priority: Ubuntu including 1 source packages (cups), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 6, released 1. https://ubuntu.com/security/CVE-2026-34978

Affected software / configurations for CVE-2026-34978

Vendor Product Version Raw CPE
openprinting cups <= 2.4.16 cpe:2.3:a:openprinting:cups:*:*:*:*:*:*:*:*

References for CVE-2026-34978

cvelogic Threat Intelligence