Is CVE-2026-43403 in the CISA KEV catalog?

No. CVE-2026-43403 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-43403?

CVE-2026-43403 has a CVSS v3 base score of 8.8 (HIGH).

What is the EPSS score for CVE-2026-43403?

CVE-2026-43403 has an EPSS score of 0.13% (3th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-43403?

Upgrade linux on debian 13 to 6.12.85-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-43403

HIGH

8.8

CVSS v3

NVD

Description

In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for ns iteration ioctls Even privileged services should not necessarily be able to see other privileged service's namespaces so they can't leak information to each other. Use may_see_all_namespaces() helper that centralizes this policy until the nstree adapts.

How to fix

Remediation Available

linuxDebian

Fixed in:6.12.85-1CVE-2026-43403

Fixed in:6.19.10-1CVE-2026-43403

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploit Intelligence

0.13%probability of exploitation in 30 days

3rdpercentile

Low risk: more likely to be exploited than 3% of all known CVEs.

References

Patch4

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-21.