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CVE Record

CVE-2025-71304: smack: /smack/doi: accept previously used values

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)

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-71304 is a Linux kernel Smack bug that can break networking for processes using non-ambient Smack labels after a previously used DOI value is written again. The reported impact is operational disruption, not code execution. Evidence points to specialized Smack, NetLabel, and CIPSO deployments.

Executive priority

Treat this as targeted operational risk. It is important for environments relying on Smack network labeling, but current evidence does not support emergency broad remediation across ordinary Linux fleets.

Technical view

The flaw is in Smack handling of /smack/doi. Reusing an old DOI can leave decommissioned DOI definitions behind, fail to re-add CIPSO state, and remove the default IPv4 NetLabel domain map. The fix clears decommissioned DOI definitions, serializes DOI updates, and preserves the old map if adding the new DOI fails.

Likely exposure

Exposure appears limited to Linux systems using Smack with NetLabel/CIPSO configuration and writable /smack/doi administration. The source does not identify affected distributions, packages, cloud images, containers, or default configurations.

Exploitation context

The source demonstrates local administrative writes to /smack/doi causing networking failure for non-ambient labels. KEV is false, and the bundle provides no evidence of active exploitation, public weaponization, remote exploitation, or privilege escalation.

Researcher notes

The strongest evidence is the kernel description and stable commit references. Severity, CVSS, CWEs, exploitability beyond local DOI administration, and distribution-specific fixed versions are not provided in the bundle.

Mitigation direction

  • Check vendor kernel advisories for your distribution and supported release line.
  • Prioritize updates where Smack, NetLabel, or CIPSO are enabled in production.
  • Restrict /smack/doi administration to trusted operational paths and privileged users.
  • Avoid unnecessary DOI changes until vendor guidance or patched kernels are available.
  • Monitor systems for unexpected loss of default IPv4 NetLabel mappings.

Validation and detection

  • Inventory Linux hosts using Smack, NetLabel, or CIPSO labeling.
  • Confirm whether /smack/doi exists and is operationally managed on those hosts.
  • Compare running kernel versions against vendor-fixed kernel releases.
  • Review change history for recent DOI updates on Smack-enabled systems.
  • Check NetLabel default IPv4 domain mapping state after DOI changes.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
9Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99, e114e473771c848c3cfec05f0123e70f1cdbdc99unaffected
LinuxLinux2.6.25, 0, 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0affected
Weakness

CWE details

No CWE listed

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