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CVE-2026-99266

io_uring/zcrx: fix buffer offsets in areas above 4GB

CVSS score

—

EPSS probability

—

Risk score

—

Published

2 h ago

Patch status has not yet been verified

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Vulnerability description

DayBreach AI Explanation

Verified against sources

CVE-2026-99266 Linux Kernel io_uring/zcrx Buffer Offset Vulnerability

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

CVE-2026-99266 in the Linux kernel io_uring/zcrx component causes incorrect buffer offset calculations in areas above 4GB.

Why does it matter?

This vulnerability causes applications to read incorrect data and return unowned buffers via the refill queue.

What should be done?

  • Review the provided vendor advisories and patch commit links
  • Apply official updates for the running version
Chain of evidence and sources2 verified claims

io_zcrx_queue_cqe() fonksiyonu, net_iov_idx() üzerinden 32 bit kaydırma yaparak tampon ofsetini hesaplar.

İlk 4GB'ın ötesindeki niov değerleri için CQE uygulamayı yanlış bir tampona yönlendirir.

Show the technical text from the sources

In the Linux kernel, the following vulnerability has been resolved: io_uring/zcrx: fix buffer offsets in areas above 4GB io_zcrx_queue_cqe() computes the offset of the buffer in its area from net_iov_idx(), which is an unsigned int, so the shift is done in 32 bits and only the result is widened to the u64 that goes into the CQE. An area can be up to 1TB in size. For every niov beyond the first 4GB the CQE points the application at a buffer 4GB, or a multiple of that, below the one which has the data. It reads the wrong data, and then returns a buffer it doesn't own via the refill queue while the real one is never given back.

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-99266 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1linuxLinux View
2linuxLinux View
Total affected vendors: 1|Products: 2

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
The sources have not yet published a verified CVSS metric.

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-99266 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-99266 weaknesses.

Official Sources and Advisories

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

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CVE-2026-99266 · io_uring/zcrx: fix buffer offsets in areas…