How severe is CVE-2026-43258?

CVE-2026-43258 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-43258 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-43258?

CVE-2026-43258 primarily affects Linux Linux Kernel. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-43258?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-43258 have an EU (EUVD) identifier?

Yes. CVE-2026-43258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27817.

When was CVE-2026-43258 published?

CVE-2026-43258 was published on 2026-05-06 and last updated on 2026-06-17.

CVE-2026-43258

CVE-2026-43258 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27817
Weakness: CWE-787
Affected product: Linux Linux Kernel
Published: 2026-05-06
Last modified: 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: alpha: fix user-space corruption during memory compaction Alpha systems can suffer sporadic user-space crashes and heap corruption when memory compaction is enabled. Symptoms include SIGSEGV, glibc allocator failures (e.g. "unaligned tcache chunk"), and compiler internal errors. The failures disappear when compaction is disabled or when using global TLB invalidation. The root cause is insufficient TLB shootdown during page migration. Alpha relies on ASN-based MM context rollover for instruction cache coherency, but this alone is not sufficient to prevent stale data or instruction translations from surviving migration. Fix this by introducing a migration-specific helper that combines: - MM context invalidation (ASN rollover), - immediate per-CPU TLB invalidation (TBI), - synchronous cross-CPU shootdown when required. The helper is used only by migration/compaction paths to avoid changing global TLB semantics. Additionally, update flush_tlb_other(), pte_clear(), to use READ_ONCE()/WRITE_ONCE() for correct SMP memory ordering. This fixes observed crashes on both UP and SMP Alpha systems.

Frequently asked questions

What is CVE-2026-43258?: In the Linux kernel, the following vulnerability has been resolved: alpha: fix user-space corruption during memory compaction Alpha systems can suffer sporadic user-space crashes and heap corruption when memory compaction is enabled. Symptoms include SIGSEGV, glibc allocator failures (e.g. "unaligned tcache chunk"), and compiler internal errors. The failures disappear when compaction is disabled or when using global TLB invalidation. The root cause is insufficient TLB shootdown during page migration. Alpha relies on ASN-based MM context rollover for instruction cache coherency, but this alone is not sufficient to prevent stale data or instruction translations from surviving migration. Fix this by introducing a migration-specific helper that combines: - MM context invalidation (ASN rollover), - immediate per-CPU TLB invalidation (TBI), - synchronous cross-CPU shootdown when required. The helper is used only by migration/compaction paths to avoid changing global TLB semantics. Additionally, update flush_tlb_other(), pte_clear(), to use READ_ONCE()/WRITE_ONCE() for correct SMP memory ordering. This fixes observed crashes on both UP and SMP Alpha systems.
How severe is CVE-2026-43258?: CVE-2026-43258 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-43258 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-43258?: CVE-2026-43258 primarily affects Linux Linux Kernel. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-43258?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-43258 have an EU (EUVD) identifier?: Yes. CVE-2026-43258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27817.
When was CVE-2026-43258 published?: CVE-2026-43258 was published on 2026-05-06 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.16:rc7:*:*:*:*:*:*

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