High [CVE-2026-68159] Linux kernel: libceph stack out-of-bounds write via crafted OSDMap
This high-severity Red Hat Linux advisory covers CVE-2026-68159 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8.
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Summary
In the Linux kernel, the following vulnerability has been resolved: libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE __decode_pg_temp() decodes an user-controlled length but only rejects values large enough to overflow the allocation; it does not bound it to CEPH_PG_MAX_SIZE.
The helper backs both pg_temp and pg_upmap decoding, and apply_upmap()/get_temp_osds() later copy the decoded list into the fixed-size on-stack array struct ceph_osds.osds[CEPH_PG_MAX_SIZE]. A monitor that sends an OSDMap with a pg_temp/pg_upmap entry longer than 32 thus causes a stack out-of-bounds write.
An OSD set for a single PG can never exceed CEPH_PG_MAX_SIZE, so reject longer entries at decode time. The bound is well below the old overflow threshold, so it also covers the allocation-size overflow the previous check guarded against.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; and 3 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 30 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 30 days ago·verify at source
Mitigation checklist
- If the system does not require the `libceph` module for Ceph cluster connectivity, prevent the `ceph` kernel module from loading by blacklisting it. Create a file `/etc/modprobe.d/ceph.conf` with the content `blacklist ceph`. After creating the file, regenerate the initramfs using `dracut -f -v` and reboot the system for the changes to take effect. If `libceph` is in use, restrict network access to Ceph monitors to trusted hosts through firewall rules to reduce the attack surface.
Official advisory · high-confidence parse· fetched 30 days ago·verify at source
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