netfilter: nf_conntrack_h323: fix OOB read in decode_choice()

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Summary

CVECVE-2026-43233
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 12:16:43 UTC
Updated2026-05-12 19:03:56 UTC
DescriptionIn 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().

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS: 0.000520000 probability, percentile 0.160740000 (date 2026-05-11)

Problem Types: CWE-125

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041 git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa 2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa 81f2fc5b0d0cf4696146f00f837596d10b92dead git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa 7ef82863d42261817a6394c6c881bd6757a70f16 git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa 53d32735d77ab56cc3fc7bd53a7d099418f19be1 git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa f0a83d0a4b7c127d32ac06d607a9214937716129 git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa 35f1943d242e1b9f0b6e91c0c93bfb293a9f8224 git Not specified
CNA Linux Linux affected ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa baed0d9ba91d4f390da12d5039128ee897253d60 git Not specified
CNA Linux Linux affected 4.15 Not specified
CNA Linux Linux unaffected 4.15 semver Not specified
CNA Linux Linux unaffected 5.10.252 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.202 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.165 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.128 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.75 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.16 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.6 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/53d32735d77ab56cc3fc7bd53a7d099418f19be1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/7ef82863d42261817a6394c6c881bd6757a70f16 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/81f2fc5b0d0cf4696146f00f837596d10b92dead 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/35f1943d242e1b9f0b6e91c0c93bfb293a9f8224 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f0a83d0a4b7c127d32ac06d607a9214937716129 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/baed0d9ba91d4f390da12d5039128ee897253d60 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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