Linux Kernel up to 6.19.5 decode_choice buffer overflow

CVSS Meta Temp Score
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CTI Interest Score
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7.6$5k-$25k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.19.5. The impacted element is the function decode_choice. Such manipulation leads to buffer overflow. This vulnerability is uniquely identified as CVE-2026-43233. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.5. It has been rated as critical. Affected by this issue is the function decode_choice. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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().

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-43233 since 05/01/2026. The exploitation is known to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 07/10/2026).

The vulnerability scanner Nessus provides a plugin with the ID 326222 (EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16 or 6.19.6 eliminates this vulnerability. Applying the patch bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041/2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a/81f2fc5b0d0cf4696146f00f837596d10b92dead/7ef82863d42261817a6394c6c881bd6757a70f16/53d32735d77ab56cc3fc7bd53a7d099418f19be1/f0a83d0a4b7c127d32ac06d607a9214937716129/35f1943d242e1b9f0b6e91c0c93bfb293a9f8224/baed0d9ba91d4f390da12d5039128ee897253d60 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (326222). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 326222
Nessus Name: EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.252/5.15.202/6.1.165/6.6.128/6.12.75/6.18.16/6.19.6
Patch: bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041/2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a/81f2fc5b0d0cf4696146f00f837596d10b92dead/7ef82863d42261817a6394c6c881bd6757a70f16/53d32735d77ab56cc3fc7bd53a7d099418f19be1/f0a83d0a4b7c127d32ac06d607a9214937716129/35f1943d242e1b9f0b6e91c0c93bfb293a9f8224/baed0d9ba91d4f390da12d5039128ee897253d60

Timelineinfo

05/01/2026 CVE reserved
05/06/2026 +5 days Advisory disclosed
05/06/2026 +0 days VulDB entry created
07/10/2026 +65 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-43233 (🔒)
GCVE (CVE): GCVE-0-2026-43233
GCVE (VulDB): GCVE-100-361412

Entryinfo

Created: 05/06/2026 16:35
Updated: 07/10/2026 14:43
Changes: 05/06/2026 16:35 (58), 07/10/2026 14:43 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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