CyberSecBulletin
CVE-2023-53619NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2023-53619 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7, 00716f25f9697d02a0d9bd622575c7c7321ba3d0, 61c7a5256543ae7d24cd9d21853d514c8632e1e9 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 0.22% 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 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7 or 00716f25f9697d02a0d9bd622575c7c7321ba3d0 or 61c7a5256543ae7d24cd9d21853d514c8632e1e9 or 8289d422f5e484efe4a565fe18e862ecd621c175, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.14.322 or 4.19.291 or 5.4.251 or 5.10.188, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 00716f25f9697d02a0d9bd622575c7c7321ba3d0; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 61c7a5256543ae7d24cd9d21853d514c8632e1e9; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 8289d422f5e484efe4a565fe18e862ecd621c175; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 05561f822f27b9fa88fa5504ddec34bf38833034; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7; 12f7a505331e6b2754684b509f2ac8f0011ce644 up to, but not including, 6eef7a2b933885a17679eb8ed0796ddf0ee5309b; and 1 more ranges4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7, 00716f25f9697d02a0d9bd622575c7c7321ba3d0, 61c7a5256543ae7d24cd9d21853d514c8632e1e9, 8289d422f5e484efe4a565fe18e862ecd621c175, 6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566, 05561f822f27b9fa88fa5504ddec34bf38833034
LinuxLinux Kernel3.6 up to, but not including, 4.14.322; 4.15 up to, but not including, 4.19.291; 4.20 up to, but not including, 5.4.251; 5.5 up to, but not including, 5.10.188; 5.11 up to, but not including, 5.15.121; 5.16 up to, but not including, 6.1.39; 6.2 up to, but not including, 6.4.4; 6.54.14.322, 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.39

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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: Avoid nf_ct_helper_hash uses after free If nf_conntrack_init_start() fails (for example due to a register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini() clean-up path frees the nf_ct_helper_hash map. When built with NF_CONNTRACK=y, further netfilter modules (e.g: netfilter_conntrack_ftp) can still be loaded and call nf_conntrack_helpers_register(), independently of whether nf_conntrack initialized correctly. This accesses the nf_ct_helper_hash dangling pointer and causes a uaf, possibly leading to random memory corruption. This patch guards nf_conntrack_helper_register() from accessing a freed or uninitialized nf_ct_helper_hash pointer and fixes possible uses-after-free when loading a conntrack module.

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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