# CVE-2025-3576: MIT Kerberos message spoofing via RC4-HMAC-MD5 MD5 collisions

Source: https://junglewise.ai/threats/cve-2025-3576-mit-kerberos-message-spoofing-via-rc4-hmac-md5-md5-collisions  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-04-15. Updated: 2026-05-12  
License: CC BY 4.0 with a link back

CVE-2025-3576 · Severity: medium · CVSS 5.9 · Published 2025-04-15

A vulnerability in the MIT Kerberos implementation, a widely used system for secure network authentication, allows attackers to tamper with protected messages. By exploiting weaknesses in older encryption methods (RC4-HMAC-MD5), an attacker can forge digital signatures to modify data without detection. This could lead to unauthorized changes in sensitive communications or administrative commands across a corporate network.

Technologies: [Debian Linux](https://junglewise.ai/threats/technologies/debian), [Mit Krb5](https://junglewise.ai/threats/technologies/krb5). Vendors: [Debian](https://junglewise.ai/threats/vendors/debian), [Mit](https://junglewise.ai/threats/vendors/mit).

## Quick answers

**Is CVE-2025-3576 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-3576 being exploited in the wild.

**How severe is CVE-2025-3576?** Medium severity, with a CVSS score of 5.9, published 15 April 2025.

**Which products and versions are affected?** Debian Linux LTS; Mit Krb5 prior to 1.22.

**Is there a fix for CVE-2025-3576?** A patch was published on 2025-05-30: Debian LTS security update released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-3576 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2025-3576?** Check whether you run Debian Linux or Mit Krb5 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A cryptographic vulnerability exists in the MIT Kerberos (krb5) implementation of the GSSAPI mechanism when using the RC4-HMAC-MD5 encryption type. The root cause is a weakness in the MD5 checksum design that is susceptible to collision attacks. If a session negotiates or prefers RC4 over more secure algorithms like AES, a network-positioned attacker can exploit these collisions to forge Message Integrity Codes (MICs). This allows for the spoofing or tampering of GSSAPI-protected messages without the legitimate parties detecting the modification. Patches have been released by MIT and major Linux distributions including Red Hat and Debian to address this by improving checksum handling or deprecating the vulnerable algorithm.

## Affected products

- MIT krb5 prior to 1.22
- Red Hat Enterprise Linux 9.2, 9.4, 10.0
- Debian Debian Linux LTS

## Timeline

- 2025-04-15: disclosed: Initial disclosure and NVD publication
- 2025-04-15: advisory: Red Hat published initial security advisory
- 2025-05-30: patched: Debian LTS security update released
- 2025-08-12: patched: Red Hat released updated packages for RHEL 9.4

## References

- [https://access.redhat.com/errata/RHSA-2025:11487](https://access.redhat.com/errata/RHSA-2025:11487)
- [https://access.redhat.com/errata/RHSA-2025:13664](https://access.redhat.com/errata/RHSA-2025:13664)
- [https://access.redhat.com/errata/RHSA-2025:13777](https://access.redhat.com/errata/RHSA-2025:13777)
- [https://access.redhat.com/errata/RHSA-2025:15000](https://access.redhat.com/errata/RHSA-2025:15000)
- [https://access.redhat.com/errata/RHSA-2025:15001](https://access.redhat.com/errata/RHSA-2025:15001)
- [https://access.redhat.com/errata/RHSA-2025:15002](https://access.redhat.com/errata/RHSA-2025:15002)
- [https://access.redhat.com/errata/RHSA-2025:15003](https://access.redhat.com/errata/RHSA-2025:15003)

## Related threats

- [MIT krb5 NULL pointer dereference in KDC get_pac_princ_with_realm](https://junglewise.ai/threats/cve-2026-107708-mit-krb5-through-1-22-2-contains-a-null-pointer-dereference)
- [MIT krb5 integer underflow in berval2tl_data function](https://junglewise.ai/threats/cve-2026-11850-mit-krb5-integer-underflow-in-berval2tl-data-function)
- [libpng use-after-free in chunk setter functions](https://junglewise.ai/threats/cve-2026-34757-libpng-use-after-free-in-chunk-setter-functions)
- [firewalld incorrect authorization in D-Bus setters](https://junglewise.ai/threats/cve-2026-4948-firewalld-incorrect-authorization-in-d-bus-setters)
- [libtiff signed integer overflow in putcontig8bitYCbCr44tile](https://junglewise.ai/threats/cve-2026-4775-libtiff-signed-integer-overflow-in-putcontig8bitycbcr44tile)