Security Digest · Vulnerability record
CVE-2026-21531: Azure AI Language Authoring Elevation of Privilege Vulnerability can Lead to RCE
Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.
CVSS 9.8 Critical EPSS 2.6% · p85
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 2.6%, percentile 85: FIRST’s model estimates a 2.6% chance of exploitation activity in the next 30 days, higher than 85% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
azure-ai-language-conversations-authoring(PyPI) < 1.0.0b4, fixed in 1.0.0b4. Check your lockfile, including transitive dependencies.
What it is
Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.
From the GitHub advisory
Deserialization of untrusted data in the Azure AI Language Conversations Authoring client library for Python allows an unauthorized attacker to execute code over a network.
Weakness type: CWE-502.
Product: azure-ai-language-conversations-authoring (PyPI) · Assigned by: microsoft · Published: 2026-02-10
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | azure-ai-language-conversations-authoring | < 1.0.0b4 | 1.0.0b4 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | Azure AI Language Authoring | 1.0.0 < 1.0.0b4 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoft | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 2.58% probability of exploitation activity in the next 30 days; percentile 85.
Timeline
- — CVE record published by microsoft
- — GitHub-reviewed advisory GHSA-436v-jg82-p533 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- Azure SDK for Python Remote Code Execution Vulnerability msrc.microsoft.com
Vulnerability records
- GitHub Advisory GHSA-436v-jg82-p533 github.com
- CVE.org record CVE-2026-21531 cve.org
- NVD entry CVE-2026-21531 nvd.nist.gov