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Linux EUVDEUVD-2026-108777

| CVE-2026-98983
2026-10-23 Linux GHSA-vc4v-q632-x9g5
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Awaiting Data No severity or threat signals available yet. Label will update when CVSS score is published or threat intelligence arrives. Why: No CVSS yet + weak signal (CWE or non-zero EPSS).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisCVE.org

In the Linux kernel, the following vulnerability has been resolved:

unshare: don't drop active namespace references that were never taken

Active references on the namespaces of an nsproxy are taken when the nsproxy is installed into a task in switch_task_namespaces() and copy_namespaces() and dropped again by put_nsproxy() through deactivate_nsproxy().

But ksys_unshare() calls put_nsproxy() on an nsproxy that was never installed when set_cred_ucounts() fails. The new namespaces of that nsproxy go from zero to minus one and the namespaces shared with the caller lose a reference that belongs to the nsproxy the caller keeps using:

WARNING: kernel/nscommon.c:171 at __ns_ref_active_put+0x1cd/0x230 nsproxy_ns_active_put deactivate_nsproxy ksys_unshare

Afterwards the namespaces the caller lives in aren't listed by listns() anymore. set_cred_ucounts() only fails when alloc_ucounts() can't allocate and it only allocates when the real uid of the caller differs from its effective uid.

Commit cefd55bd2159 ("nsproxy: fix free_nsproxy() and simplify create_new_namespaces()") separated the two cases on purpose. nsproxy_free() frees an nsproxy that was prepared but never installed and that's what a failed setns() uses in put_nsset(). Export it and use it for a failed unshare() as well.

Affected VersionsENISA

Linux 6.18.33 <6.19
Linux 6.1.175 <6.2
Linux 813a47b0309097da71781ee4ac11922e39b67d55
Linux 7.1
Linux 6e608e3e5ce12ce7fd21e46212eccca37f917d0e
Linux 27ae6b17c9ba7ff353ab0906297f08aa845782b4
Linux patch: 0
Linux 6.6.141 <6.7
Linux a98621a0f187a934c115dcfe79a49520ae892111 <56fe03a0c05dba4c5f6a23c391f96de1614a098c
Linux a261fccdb4ac58ec5ba6aa1d92a6cc418fff301f
Linux 665dc1ed16357988d439fc5bbc860ee36f540d81
Linux 297261b343371c4f0b31055d53d285138ec21565
Linux 5.15.209 <5.16
Linux 7.0.10 <7.1
Linux a98621a0f187a934c115dcfe79a49520ae892111 <0b6f31a3c0b16066f812e94b52a704174a6f23cd
Linux 6.12.91 <6.13
Linux patch: 7.2.11
Linux patch: 7.3

Affected Packages

euvd linux fix: 5.16, 6.2, 6.7, 6.13, 6.19, 7.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Lifecycle Timeline

2
Patch available
Oct 23, 2026 - 13:17 EUVD
CVE Published
Oct 23, 2026 - 12:20 cve.org
UNKNOWN (no severity yet)

Threat Intelligence Overview

EPSS Score
0.2%
Top 91% exploitable
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity Not scored yet
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
No CVSS yet + weak signal (CWE or non-zero EPSS)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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