CyberSecBulletin
CVE-2026-68159NVD status: Received

Linux: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-68159 is a critical-severity stack-based buffer overflow 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 66eec4af1e080b695229c9a20635648a6d12fedf, 4daf06456677177f2a6044729abac59c1b49e87b, d5650ddbd4d42c1a916c8fe1a4c4cb573ef810a1 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 0.74% chance of exploitation within 30 days, higher than 55% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 66eec4af1e080b695229c9a20635648a6d12fedf or 4daf06456677177f2a6044729abac59c1b49e87b or d5650ddbd4d42c1a916c8fe1a4c4cb573ef810a1 or 42bc06c67d94d5f2a6b33294b0c4b07d8a47c515, 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
LinuxLinuxa303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, 66eec4af1e080b695229c9a20635648a6d12fedf; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, 4daf06456677177f2a6044729abac59c1b49e87b; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, d5650ddbd4d42c1a916c8fe1a4c4cb573ef810a1; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, 42bc06c67d94d5f2a6b33294b0c4b07d8a47c515; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, ebdf4b4f3b1474079980a2e5cd79ad65fb54db57; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, 590b07ceea138d49c9b64f65d263aa902d3b4730; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, e36663145abd7024f0281dfb22fdef65f185845b; a303bb0e58345fe9f7ab2f82b90266f2b5036058 up to, but not including, 9f00f9cf2be293efe899db67dc5272e3a9c62717; and 1 more ranges66eec4af1e080b695229c9a20635648a6d12fedf, 4daf06456677177f2a6044729abac59c1b49e87b, d5650ddbd4d42c1a916c8fe1a4c4cb573ef810a1, 42bc06c67d94d5f2a6b33294b0c4b07d8a47c515, ebdf4b4f3b1474079980a2e5cd79ad65fb54db57, 590b07ceea138d49c9b64f65d263aa902d3b4730

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: 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. BUG: KASAN: stack-out-of-bounds in ceph_pg_to_up_acting_osds Write of size 4 ... by task exploit kasan_report (mm/kasan/report.c:595) ceph_pg_to_up_acting_osds (net/ceph/osdmap.c:2617 net/ceph/osdmap.c:2833) calc_target (net/ceph/osd_client.c:1638) __submit_request (net/ceph/osd_client.c:2394) ceph_osdc_start_request (net/ceph/osd_client.c:2490) ceph_osdc_call (net/ceph/osd_client.c:5164) rbd_dev_image_probe (drivers/block/rbd.c:6899) do_rbd_add (drivers/block/rbd.c:7138) ... kernel BUG at net/ceph/osdmap.c:2670! [ idryomov: do the same in __decode_pg_upmap_items() ]

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

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

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 Stack-based Buffer Overflow vulnerabilities

Spotted an error? Tell us.