CVE-2023-4091

NameCVE-2023-4091
DescriptionA vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-3792-1, DSA-5525-1, DSA-5647-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
samba (PTS)bullseye (security), bullseye2:4.13.13+dfsg-1~deb11u6fixed
bookworm, bookworm (security)2:4.17.12+dfsg-0+deb12u1fixed
trixie2:4.20.2+dfsg-6fixed
sid2:4.20.2+dfsg-7fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
sambasourcebuster2:4.9.5+dfsg-5+deb10u5DLA-3792-1
sambasourcebullseye2:4.13.13+dfsg-1~deb11u6DSA-5647-1
sambasourcebookworm2:4.17.12+dfsg-0+deb12u1DSA-5525-1
sambasource(unstable)2:4.19.1+dfsg-1

Notes

https://www.samba.org/samba/security/CVE-2023-4091.html
In scope for continued Samba support
Fixed by: https://git.samba.org/?p=samba.git;a=commit;h=b08a60160e6ab8d982d31844bcbf7ab67ff3a8de (samba-4.17.12)
Fixed by: https://git.samba.org/?p=samba.git;a=commit;h=8b26f634372f11edcbea33dfd68a3d57889dfcc5 (samba-4.17.12)

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