Is CVE-2020-1045 being actively exploited?

CVE-2020-1045 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2020-1045?

CVE-2020-1045 has a CVSS 3.1 base score of 7.5 (HIGH).

CVE-2020-1045

HIGH · CVSS 7.5EPSS 5.9%EU EUVD

A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names. 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. The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.

Key facts

CVSS score: 7.5 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS score: 5.9% (93th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2022-4249)
Published: September 11, 2020
NVD last modified: June 17, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2022-4249 in the EU Vulnerability Database. Last updated in EUVD on November 18, 2024.

View on the EU Vulnerability Database

Affected products

fedoraproject / fedora
fedoraproject / fedora
microsoft / asp.net core
redhat / enterprise linux
redhat / enterprise linux aus
redhat / enterprise linux aus
redhat / enterprise linux aus
redhat / enterprise linux eus
redhat / enterprise linux eus
redhat / enterprise linux eus
redhat / enterprise linux tus
redhat / enterprise linux tus
redhat / enterprise linux tus

Certified products that may be affected

25 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Red Hat Enterprise Linux 8 NSS Cryptographic Module - Red Hat, Inc. - FIPS 140 5513 - active
Red Hat Enterprise Linux 8 Kernel Cryptographic API - Red Hat, LLC - FIPS 140 5461 - active
Red Hat Enterprise Linux 8 Kernel Cryptographic API - Red Hat, Inc. - FIPS 140 5089 - active
Red Hat Enterprise Linux 8.6 - Red Hat, Inc. - Common Criteria CCEVS-VR-VID-11309-2024 - archived
Red Hat Enterprise Linux 8 OpenSSL Cryptographic Module - Red Hat®, Inc. - FIPS 140 4642 - historical

See all 25 in the Security Certifications Explorer.

References

https://access.redhat.com/errata/RHSA-2020:3699(Third Party Advisory)
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318(Release Notes, Third Party Advisory)
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045(Patch, Vendor Advisory)
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600(Third Party Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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