Incomplete privilege drop for com.system76.CosmicGreeter.GetUserData

published 2026-03-30 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-17067

cvss: 5.8; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits: 0; none known

A Privilege Dropping / Lowering Errors/Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in cosmic-greeter can allow an attacker to regain privileges that should have been dropped and abuse them in the racy checking logic.

This issue affects cosmic-greeter before https://github.Com/pop-os/cosmic-greeter/pull/426.

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-2026-25704 updated 2026-06-28 cvss 7.0

cosmic-greeter: cosmic-greeter: Privilege escalation via TOCTOU race condition

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: none
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-03-30)

Exploit prediction

0.08% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.8	CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
CNA	4.0	5.8	CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:H/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

pop-os cosmic-greeter

Classification

Weakness

CWE-271 Privilege Dropping / Lowering Errors
CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

CVE List CVE-2026-25704
NVD CVE-2026-25704

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.

Summary