CyberSecBulletin
CVE-2026-68156NVD status: Received

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-68156 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 2334e9997308305ee4fd508fdfe6086c4150ed60, 79a273df64238a4ade8b709689a78589f755b8ef, 26f814187abceee90dbb29a02133adb4786fbb13 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.69% chance of exploitation within 30 days, higher than 54% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 2334e9997308305ee4fd508fdfe6086c4150ed60 or 79a273df64238a4ade8b709689a78589f755b8ef or 26f814187abceee90dbb29a02133adb4786fbb13 or 9d37aec9ffe4e743dabc3f84502e9723e17a30d4, whichever matches your release line, or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 2334e9997308305ee4fd508fdfe6086c4150ed60; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 79a273df64238a4ade8b709689a78589f755b8ef; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 26f814187abceee90dbb29a02133adb4786fbb13; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 9d37aec9ffe4e743dabc3f84502e9723e17a30d4; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 75e82e8944ac1efe9fdb88bd2f14d9a031282bdf; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 0060ec912292a550198d8d18ac95b433c92a7091; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 5ecfcd5c05866f185357700b81b461dae4f5ebb2; 0bed9b5c523d577378b6f83eab5835fe30c27208 up to, but not including, 937d61f86d377a3aa578adae7a3dfcecdddf9d89; and 5 more ranges2334e9997308305ee4fd508fdfe6086c4150ed60, 79a273df64238a4ade8b709689a78589f755b8ef, 26f814187abceee90dbb29a02133adb4786fbb13, 9d37aec9ffe4e743dabc3f84502e9723e17a30d4, 75e82e8944ac1efe9fdb88bd2f14d9a031282bdf, 0060ec912292a550198d8d18ac95b433c92a7091

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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