CyberSecBulletin
CVE-2026-53228NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-53228 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 fddd41445a0537b093e6b3f6232c9933cad1e48b, 1132e5edc2866c3530be17622153a597095f0e43, 9c67b44edb3598d234efae6e44649eb993c03da5 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 0.58% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to fddd41445a0537b093e6b3f6232c9933cad1e48b or 1132e5edc2866c3530be17622153a597095f0e43 or 9c67b44edb3598d234efae6e44649eb993c03da5 or 0bfa7bba1f41aaf5f0604dc712bb4701493e3aa0, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.
  3. 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
LinuxLinux14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, fddd41445a0537b093e6b3f6232c9933cad1e48b; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, 1132e5edc2866c3530be17622153a597095f0e43; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, 9c67b44edb3598d234efae6e44649eb993c03da5; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, 0bfa7bba1f41aaf5f0604dc712bb4701493e3aa0; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, 59f80c919713250fe5d25a4d9aea4e49580fa1d4; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, 2fa49b2715e1bad12ce3b0fa64e234d9582c8193; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, cb658c2f5f7977c2a1c77c9f239f4bc8196edb5c; 14909664e4e192f4c6f6fcdccd9919af7cf783ab up to, but not including, f0e42f0c4337b1f220de1ddd63f47197c7dee4de; and 1 more rangesfddd41445a0537b093e6b3f6232c9933cad1e48b, 1132e5edc2866c3530be17622153a597095f0e43, 9c67b44edb3598d234efae6e44649eb993c03da5, 0bfa7bba1f41aaf5f0604dc712bb4701493e3aa0, 59f80c919713250fe5d25a4d9aea4e49580fa1d4, 2fa49b2715e1bad12ce3b0fa64e234d9582c8193
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel3.18 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.15.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36

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: ipv6: sit: reload inner IPv6 header after GSO offloads ipip6_tunnel_xmit() caches the inner IPv6 header pointer at function entry and continues using it after iptunnel_handle_offloads(). For GSO skbs, iptunnel_handle_offloads() calls skb_header_unclone(). When the skb header is cloned, skb_header_unclone() can call pskb_expand_head(), which may move the skb head. The pskb_expand_head() contract requires pointers into the skb header to be reloaded after the call. If the later skb_realloc_headroom() branch is not taken, SIT uses the stale iph6 pointer to read the inner hop limit and DS field. That can read from a freed skb head after the old head's remaining clone is released. Reload iph6 after the offload helper succeeds and before subsequent reads from the inner IPv6 header. Keep the existing reload after skb_realloc_headroom(), since that branch can also replace the skb.

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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