CVE-2025-71304

Published May 27, 2026

Last updated 10 days ago

CVSS medium 5.5

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: smack: /smack/doi: accept previously used values Writing to /smack/doi a value that has ever been written there in the past disables networking for non-ambient labels. E.g. # cat /smack/doi 3 # netlabelctl -p cipso list Configured CIPSO mappings (1) DOI value : 3 mapping type : PASS_THROUGH # netlabelctl -p map list Configured NetLabel domain mappings (3) domain: "_" (IPv4) protocol: UNLABELED domain: DEFAULT (IPv4) protocol: CIPSO, DOI = 3 domain: DEFAULT (IPv6) protocol: UNLABELED # cat /smack/ambient _ # cat /proc/$$/attr/smack/current _ # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.964 ms # echo foo >/proc/$$/attr/smack/current # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.956 ms unknown option 86 # echo 4 >/smack/doi # echo 3 >/smack/doi !> [ 214.050395] smk_cipso_doi:691 cipso add rc = -17 # echo 3 >/smack/doi !> [ 249.402261] smk_cipso_doi:678 remove rc = -2 !> [ 249.402261] smk_cipso_doi:691 cipso add rc = -17 # ping -c1 10.1.95.12 !!> ping: 10.1.95.12: Address family for hostname not supported # echo _ >/proc/$$/attr/smack/current # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.617 ms This happens because Smack keeps decommissioned DOIs, fails to re-add them, and consequently refuses to add the “default” domain map: # netlabelctl -p cipso list Configured CIPSO mappings (2) DOI value : 3 mapping type : PASS_THROUGH DOI value : 4 mapping type : PASS_THROUGH # netlabelctl -p map list Configured NetLabel domain mappings (2) domain: "_" (IPv4) protocol: UNLABELED !> (no ipv4 map for default domain here) domain: DEFAULT (IPv6) protocol: UNLABELED Fix by clearing decommissioned DOI definitions and serializing concurrent DOI updates with a new lock. Also: - allow /smack/doi to live unconfigured, since adding a map (netlbl_cfg_cipsov4_map_add) may fail. CIPSO_V4_DOI_UNKNOWN(0) indicates the unconfigured DOI - add new DOI before removing the old default map, so the old map remains if the add fails (2008-02-04, Casey Schaufler)
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

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References

Sources include official advisories and independent security research.