cbcvebase.
CVE-2026-43233
published 2026-05-06

CVE-2026-43233: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_choice() In decode_choice(), the…

PriorityP346high8.2CVSS 3.1
AVNACLPRNUINSUCLINAH
EPSS
0.46%
37.2th percentile
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().

Affected

45 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < 2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < 81f2fc5b0d0cf4696146f00f837596d10b92dead81f2fc5b0d0cf4696146f00f837596d10b92dead
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < 7ef82863d42261817a6394c6c881bd6757a70f167ef82863d42261817a6394c6c881bd6757a70f16
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < 53d32735d77ab56cc3fc7bd53a7d099418f19be153d32735d77ab56cc3fc7bd53a7d099418f19be1
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < f0a83d0a4b7c127d32ac06d607a9214937716129f0a83d0a4b7c127d32ac06d607a9214937716129
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < 35f1943d242e1b9f0b6e91c0c93bfb293a9f822435f1943d242e1b9f0b6e91c0c93bfb293a9f8224
linuxlinux>= ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa < baed0d9ba91d4f390da12d5039128ee897253d60baed0d9ba91d4f390da12d5039128ee897253d60
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 4.15.1 < 5.10.2525.10.252
linuxlinux_kernel>= 5.11 < 5.15.2025.15.202
linuxlinux_kernel>= 5.16 < 6.1.1656.1.165
linuxlinux_kernel>= 6.13 < 6.18.166.18.16
linuxlinux_kernel>= 6.19 < 6.19.66.19.6
linuxlinux_kernel>= 6.2 < 6.6.1286.6.128
linuxlinux_kernel>= 6.7 < 6.12.756.12.75
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-6.8
ubuntulinux-aws-fips
ubuntulinux-azure-fips
ubuntulinux-fips

CVSS provenance

nvdv3.18.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
vendor_ubuntu8.8HIGH
vendor_redhat7.0MEDIUM
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