CyberSecBulletin
CVE-2026-64554NVD status: Analyzed

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-64554 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 8c10778ec674b67a07ea042fcba64270f3f38a5a, 2731efa6364e47934c96eb69e01ea131e8af8030, 00c06ef8c018493943891a7d0ca82b71b24f3180 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 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 8c10778ec674b67a07ea042fcba64270f3f38a5a or 2731efa6364e47934c96eb69e01ea131e8af8030 or 00c06ef8c018493943891a7d0ca82b71b24f3180 or c141f69d0a0fb16964dbc293650047e69bda8af7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 8c10778ec674b67a07ea042fcba64270f3f38a5a; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 2731efa6364e47934c96eb69e01ea131e8af8030; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 00c06ef8c018493943891a7d0ca82b71b24f3180; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, c141f69d0a0fb16964dbc293650047e69bda8af7; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, f2e6596d10783557aeb9668da2a3b4d19deb2001; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 1c4f67c89fd27c4df4c70b135c2c59627698b3c0; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 4ac981a8b7ce7aec99a52d08f8a8953e8e120067; 764dd163ac922f8683b5bcd3007251ce7b26cd33 up to, but not including, 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d; and 1 more ranges8c10778ec674b67a07ea042fcba64270f3f38a5a, 2731efa6364e47934c96eb69e01ea131e8af8030, 00c06ef8c018493943891a7d0ca82b71b24f3180, c141f69d0a0fb16964dbc293650047e69bda8af7, f2e6596d10783557aeb9668da2a3b4d19deb2001, 1c4f67c89fd27c4df4c70b135c2c59627698b3c0
LinuxLinux Kernel5.3 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.5; 7.25.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40

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
AdjacentThe attacker must be on the same local network segment.
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:A/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: netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment() br_ip6_fragment() gets prevhdr, a pointer into the skb head, from ip6_find_1stfragopt(), then calls skb_checksum_help(). For a cloned skb skb_checksum_help() reallocates the head via pskb_expand_head(), leaving prevhdr dangling. It is later dereferenced in ip6_frag_next(), causing a use-after-free write. Save prevhdr's offset before skb_checksum_help() and recompute it after, like commit ef0efcd3bd3f ("ipv6: Fix dangling pointer when ipv6 fragment"). BUG: KASAN: slab-use-after-free in ip6_frag_next (net/ipv6/ip6_output.c:857) Write of size 1 at addr ffff888013ff5016 by task exploit/141 Call Trace: ... kasan_report (mm/kasan/report.c:595) ip6_frag_next (net/ipv6/ip6_output.c:857) br_ip6_fragment (net/ipv6/netfilter.c:212) nf_ct_bridge_post (net/bridge/netfilter/nf_conntrack_bridge.c:407) nf_hook_slow (net/netfilter/core.c:619) br_forward_finish (net/bridge/br_forward.c:66) __br_forward (net/bridge/br_forward.c:115) maybe_deliver (net/bridge/br_forward.c:191) br_flood (net/bridge/br_forward.c:245) br_handle_frame_finish (net/bridge/br_input.c:229) br_handle_frame (net/bridge/br_input.c:442) ... packet_sendmsg (net/packet/af_packet.c:3114) ... do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt

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: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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