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FreeBSD-SA-26:60.ppp                                        Security Advisory
                                                          The FreeBSD Project

Topic:          Multiple vulnerabilities in ppp(8)

Category:       core
Module:         ppp
Announced:      2026-08-25
Credits:        Robert Morris
Credits:        Décio Brandão (0xDBJ)
Credits:        Joshua Rogers
Credits:        Reo Shiseki
Affects:        All supported versions of FreeBSD.
Corrected:      2026-08-24 18:47:44 UTC (stable/15, 15.1-STABLE)
                2026-08-25 16:01:27 UTC (releng/15.1, 15.1-RELEASE-p3)
                2026-08-25 16:01:07 UTC (releng/15.0, 15.0-RELEASE-p13)
                2026-08-24 18:49:06 UTC (stable/14, 14.4-STABLE)
                2026-08-25 16:00:28 UTC (releng/14.4, 14.4-RELEASE-p9)
CVE Name:       CVE-2026-58095, CVE-2026-58096, CVE-2026-58097

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.

I.   Background

ppp(8) is a user-space Point-to-Point Protocol (PPP) implementation
used to establish network connections over serial and dial-up links.
It supports the Multilink PPP (MP) extension, which uses endpoint
discriminators to identify individual links within a bundle.

The ppp(8) executable is installed setuid root.  However, unprivileged
users must belong to the "network" group in order to execute it.

II.  Problem Description

ppp(8) contained three memory safety errors in its handling of
multilink endpoint discriminator options.

mp_Enddisc() used incorrect length calculations when formatting
endpoint discriminator addresses for display, allowing a received
endpoint option to overflow a global result buffer.  [CVE-2026-58095]

LcpDecodeConfig() did not validate the length of received endpoint
discriminator options against the minimum required by RFC 1717.
Undersized options would trigger an out-of-bounds write.
[CVE-2026-58096]

mp_SetEnddisc() copied a user-supplied PSN endpoint value without
length validation, allowing a buffer overflow via the ppp(8) command
interface.  [CVE-2026-58097]

III. Impact

A malicious PPP peer can exploit CVE-2026-58095 and CVE-2026-58096 to
crash ppp(8) or potentially execute arbitrary code as root.  A local
user with access to the ppp(8) command interface can exploit
CVE-2026-58097 similarly.

IV.  Workaround

No workaround is available.  Systems that do not use ppp(8) are not
affected.

V.   Solution

Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.
Restart any running ppp(8) instances, or reboot the system.

Perform one of the following:

1) To update your vulnerable system installed from base system packages:

Systems running a 15.0-RELEASE or later version of FreeBSD on the amd64 or
arm64 platforms, which were installed using base system packages, can be
updated via the pkg(8) utility:

# pkg upgrade -r FreeBSD-base

2) To update your vulnerable system installed from binary distribution sets:

Systems running a RELEASE version of FreeBSD on the amd64 or arm64 platforms
which were not installed using base system packages can be updated via the
freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch https://security.FreeBSD.org/patches/SA-26:60/ppp.patch
# fetch https://security.FreeBSD.org/patches/SA-26:60/ppp.patch.asc
# gpg --verify ppp.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch -E -p0 < /path/to/patch

c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.

Restart any running ppp(8) instances, or reboot the system.

VI.  Correction details

This issue is corrected as of the corresponding Git commit hash in the
following stable and release branches:

Branch/path                             Hash                     Revision
- -------------------------------------------------------------------------
stable/15/                              dd2da2552346    stable/15-n285097
releng/15.1/                            5c00c1e02276  releng/15.1-n283607
releng/15.0/                            4ad6d3b4ccb3  releng/15.0-n281110
stable/14/                              55ee29bf3515    stable/14-n275008
releng/14.4/                            8544e4ce677f  releng/14.4-n273762
- -------------------------------------------------------------------------

Run the following command to see which files were modified by a
particular commit:

# git show --stat <commit hash>

Or visit the following URL, replacing NNNNNN with the hash:

<URL:https://cgit.freebsd.org/src/commit/?id=NNNNNN>

To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:

# git rev-list --count --first-parent HEAD

VII. References

<URL:https://www.cve.org/CVERecord?id=CVE-2026-58095>
<URL:https://www.cve.org/CVERecord?id=CVE-2026-58096>
<URL:https://www.cve.org/CVERecord?id=CVE-2026-58097>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-26:60.ppp.asc>
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