CVE-2026-43233

What it is

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_choice() In decode_choice(), the boundary check before get_len() uses the variable `len`, which is still 0 from its initialization at the top of the function: unsigned int type, ext, len = 0; ... if (ext || (son->attr & OPEN)) { BYTE_ALIGN(bs); if (nf_h323_error_boundary(bs, len, 0)) /* len is 0 here */ return H323_ERROR_BOUND; len = get_len(bs); /* OOB read */ When the bitstream is exactly consumed (bs->cur == bs->end), the check nf_h323_error_boundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end), which is false. The subsequent get_len() call then dereferences *bs->cur++, reading 1 byte past the end of the buffer. If that byte has bit 7 set, get_len() reads a second byte as well. This can be triggered remotely by sending a crafted Q.931 SETUP message with a User-User Information Element containing exactly 2 bytes of PER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with the nf_conntrack_h323 helper active. The decoder fully consumes the PER buffer before reaching this code path, resulting in a 1-2 byte heap-buffer-overflow read confirmed by AddressSanitizer. Fix this by checking for 2 bytes (the maximum that get_len() may read) instead of the uninitialized `len`. This matches the pattern used at every other get_len() call site in the same file, where the caller checks for 2 bytes of available data before calling get_len().

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-06 12:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-19 20:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 8.2 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-05-06 12:16 UTC

Last modified

2026-10-19 20:18 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Modified

Affected

• Linux Kernel < 5.10.252
• Linux Kernel < 5.15.202
• Linux Kernel < 6.1.165
• Linux Kernel < 6.6.128
• Linux Kernel < 6.12.75
• Linux Kernel < 6.18.16
• Linux Kernel < 6.19.6
• Linux Kernel 4.15

Attack profile CVSS 3.1 · 8.2

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-43233.md and follow it. Check whether this project is affected by CVE-2026-43233. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge