CVE-2020-1045

Microsoft ASP.NET Core Security Feature Bypass Vulnerability

HIGH
7.5
CVSS Score
Published: September 11, 2020 at 12:00 AM UTC
Updated: June 17, 2026 at 03:00 AM UTC
6 products affected across 3 vendorsFedoraEnterprise LinuxEnterprise Linux Eus

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Severity
HIGH7.5
Exploit prediction
EPSS 6%
SSVC
No known exploit

Description

<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p> <p>The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker to set a second cookie with the name being percent encoded.</p> <p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.0 ≤ v < publication2.1 ≤ v ≤ 2.1.213.0 ≤ v < publication3.1 ≤ v < 3.1.82.02.1*3.03.1
Affected range stops below 3.1.8, so it looks safe — our inference, not a vendor statement
Affected range stops below publication, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHmicrosoft
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfo

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