CVE-2015-5296

CVE-2015-5296 is a medium-severity vulnerability in Samba with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 3.x base score 5.4)
• CVSS v2: 4.3
• EPSS exploit prediction: 7% (94th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Samba
• Published: 2015-12-29
• Last modified: 2026-06-17

Description

Samba 3.x and 4.x before 4.1.22, 4.2.x before 4.2.7, and 4.3.x before 4.3.3 supports connections that are encrypted but unsigned, which allows man-in-the-middle attackers to conduct encrypted-to-unencrypted downgrade attacks by modifying the client-server data stream, related to clidfs.c, libsmb_server.c, and smbXcli_base.c.

Frequently asked questions

What is CVE-2015-5296?

Samba 3.x and 4.x before 4.1.22, 4.2.x before 4.2.7, and 4.3.x before 4.3.3 supports connections that are encrypted but unsigned, which allows man-in-the-middle attackers to conduct encrypted-to-unencrypted downgrade attacks by modifying the client-server data stream, related to clidfs.c, libsmb_server.c, and smbXcli_base.c.

How severe is CVE-2015-5296?

CVE-2015-5296 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2015-5296 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-5296?

CVE-2015-5296 primarily affects Samba. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-5296?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-5296 published?

CVE-2015-5296 was published on 2015-12-29 and last updated on 2026-06-17.

References

• http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174076.html
• http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174391.html
• http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00019.html
• http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00020.html
• http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00032.html
• http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00033.html
• http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00002.html
• http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00017.html
• http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00042.html
• http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00047.html
• http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00048.html
• http://www.debian.org/security/2016/dsa-3433
• http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
• http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
• http://www.securityfocus.com/bid/79732
• http://www.securitytracker.com/id/1034493
• http://www.ubuntu.com/usn/USN-2855-1
• http://www.ubuntu.com/usn/USN-2855-2
• https://bugzilla.redhat.com/show_bug.cgi?id=1290292
• https://git.samba.org/?p=samba.git%3Ba=commit%3Bh=1ba49b8f389eda3414b14410c7fbcb4041ca06b1
• https://git.samba.org/?p=samba.git%3Ba=commit%3Bh=a819d2b440aafa3138d95ff6e8b824da885a70e9
• https://git.samba.org/?p=samba.git%3Ba=commit%3Bh=d724f835acb9f4886c0001af32cd325dbbf1f895
• https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05115993
• https://security.gentoo.org/glsa/201612-47
• https://www.samba.org/samba/security/CVE-2015-5296.html

Affected products (7)

• cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:-:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:15.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*

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