High [CVE-2026-68156] refresh auth->authorizer_buf{,_len} after authorizer update
This high-severity Red Hat Linux advisory covers CVE-2026-68156 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: refresh auth->authorizer_buf{,_len} after authorizer update ceph_x_create_authorizer() caches au->buf->vec.iov_base and au->buf->vec.iov_len in struct ceph_auth_handshake.
These cached values are then used by the messenger connect code when sending the authorizer. ceph_x_update_authorizer() can rebuild the authorizer when a newer service ticket is available. If the rebuilt authorizer no longer fits in the existing buffer, ceph_x_build_authorizer() drops its reference to au->buf and allocates a new one.
If this is the final reference, ceph_buffer_put() frees the old ceph_buffer and its vec.iov_base, but auth->authorizer_buf still points at that freed memory. A subsequent msgr1 reconnect can therefore queue the stale pointer and trigger a KASAN slab-use-after-free in _copy_from_iter() while tcp_sendmsg() copies the authorizer.
Refresh auth->authorizer_buf and auth->authorizer_buf_len after a successful authorizer rebuild so the messenger sends the current buffer. During an authorizer update, if the authorizer is rebuilt, a stale pointer to a freed memory region can be retained.
A remote attacker could exploit this by triggering a specific network reconnection, leading to a use-after-free vulnerability. This memory corruption could result in a system crash or denial of service.
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
- To mitigate this vulnerability, prevent the `ceph` kernel module from loading if Ceph client functionality is not in use. Create a file `/etc/modprobe.d/ceph.conf` with `install ceph /bin/true`. If the module is currently loaded, unload it using `rmmod ceph`. A system reboot is required for the changes to take full effect and ensure the module is not reloaded. Unloading the `ceph` module will impact systems actively using Ceph client features.
Official advisory · high-confidence parse· fetched 30 days ago·verify at source
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