Patch tracker / CVE reference / CVE-2026-5435

CVE-2026-5435

A security vulnerability affecting azl3 glibc 2.38-19 on Azure Linux 3.0.

Risk summary

High

8.6

CVSS v3 base

High

Severity

Not listed

Actively exploited

High severity Microsoft vulnerability, CVSS 8.6.

Senserva AI read on CVE-2026-5435 How to fix CVE-2026-5435 Change history Admin questions

Senserva AI Opinion for CVE-2026-5435

CVE-2026-5435 is a High severity (CVSS 8.6) buffer overflow in the ns_sprintrrf TSIG handling path within glibc, affecting glibc 2.38-19 and 2.38-20 on Azure Linux 3.0 and glibc 2.35-10 on CBL Mariner 2.0. Because it sits in DNS TSIG signature formatting code inside glibc, any resolver or service on these images that processes signed DNS records could be exposed. There is no confirmed exploitation in the wild and no ransomware association at this time.

Do this: Patch glibc on your Azure Linux 3.0 and CBL Mariner 2.0 hosts to a fixed build past 2.38-20 and 2.35-10, then restart or rebuild affected containers and services.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-5435

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I am an IT admin assessing a vulnerability. Facts for CVE-2026-5435 (source: https://senserva.com/cve/CVE-2026-5435.html, data from MSRC, CISA KEV and NVD, refreshed once a day (early morning US Central)):
- CVE-2026-5435: High severity Microsoft vulnerability, CVSS 8.6
- Potential buffer overflow in ns_sprintrrf TSIG handling path
- Actively exploited (CISA KEV): no
- Affected: azl3 glibc 2.38-19 on Azure Linux 3.0, azl3 glibc 2.38-20 on Azure Linux 3.0, cbl2 glibc 2.35-10
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) What to patch or mitigate first. 4) How to check whether my devices are exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Schedule normally

No exploitation observed: not in the CISA KEV catalog, EPSS under 1%.

No vendor fix is mapped yet. This page refreshes daily and will name the patch the day one is published.

Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Updated September 12, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2026-5435

Published: 2026-04-29
Last revised: 2026-09-09
Changes tracked: 7

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

How to fix CVE-2026-5435

Apply the latest Microsoft security update for the affected product. Most environments deliver it automatically through Intune update rings, Windows Update for Business, Windows Autopatch, or WSUS; for a manual install, download from the Microsoft Update Catalog. The MSRC advisory lists the exact patched build per product.

Microsoft MSRC advisory NVD detail

Common questions about CVE-2026-5435

Is CVE-2026-5435 actively exploited?

It is not currently listed in the CISA Known Exploited Vulnerabilities catalog. That can change: unexploited CVEs regularly get weaponized months after disclosure, which is why patching on your normal cadence matters.

What fixes CVE-2026-5435?

Microsoft ships the fix in its security updates. Apply the latest cumulative or security update for the affected product through Windows Update, Intune, Windows Update for Business, or the Microsoft Update Catalog, and see the MSRC advisory below for the exact build.

Which products are affected by CVE-2026-5435?

azl3 glibc 2.38-19 on Azure Linux 3.0, azl3 glibc 2.38-20 on Azure Linux 3.0, cbl2 glibc 2.35-10.

Can I ask my own AI about CVE-2026-5435?

Yes. This page includes a free, ready-to-paste AI prompt with CVE-2026-5435's key facts: severity, CVSS, CISA KEV status, and the affected products. Copy it into Claude, ChatGPT, or Copilot for a triage plan.

Scope and sources

Affected products

Authoritative references

CVE record NVD detail Microsoft MSRC

Every Microsoft CVE and the patches that fix it, ranked by real-world risk: the Microsoft Patch Tracker. The full searchable CVE reference: CVE and vulnerability management.