Krb5: kerberos rc4-hmac-md5 checksum vulnerability enabling message spoofing via md5 collisions

Description

A vulnerability in the MIT Kerberos implementation allows GSSAPI-protected messages using RC4-HMAC-MD5 to be spoofed due to weaknesses in the MD5 checksum design. If RC4 is preferred over stronger encryption types, an attacker could exploit MD5 collisions to forge message integrity codes. This may lead to unauthorized message tampering.

Timeline

Scores

EPSS (exploitation in 30 days)

0.36% · top 70% of all CVEs (11 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.9.

Affected products

• krb5

  • affected < 1.22

• Red Hat · Red Hat Enterprise Linux 10

  • unaffected 0:1.21.3-8.el10_0 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:1.18.2-32.el8_10 – < *

• Red Hat · Red Hat Enterprise Linux 8.2 Advanced Update Support

  • unaffected 0:1.17-19.el8_2.3 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

  • unaffected 0:1.18.2-9.el8_4.3 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

  • unaffected 0:1.18.2-9.el8_4.3 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

  • unaffected 0:1.18.2-16.el8_6.4 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Telecommunications Update Service

  • unaffected 0:1.18.2-16.el8_6.4 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions

  • unaffected 0:1.18.2-16.el8_6.4 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 0:1.18.2-26.el8_8.5 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 0:1.18.2-26.el8_8.5 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.21.1-8.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.21.1-8.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

  • unaffected 0:1.19.1-16.el9_0.4 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:1.20.1-9.el9_2.3 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Extended Update Support

  • unaffected 0:1.21.1-2.el9_4.2 – < *

• Red Hat · Red Hat Discovery 2

  • unaffected 2.0.0-1752592913 – < *

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

• Red Hat · Red Hat Enterprise Linux 7

  All versions: unknown

• Red Hat · Red Hat OpenShift Container Platform 4

  All versions: affected

• Red Hat · Red Hat OpenShift Container Platform 4

  All versions: affected

What to do

Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2025-10925 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2025-3576](https://cveledger.app/badge/CVE-2025-3576.svg)](https://cveledger.app/cve/CVE-2025-3576)

Record last updated 5 Nov 2026, 14:29 UTC.