CVE-2024-26851

MEDIUM
Published Apr 17, 2024 Modified May 12, 2026 CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: Add protection for bmp length out of range UBSAN load reports an exception of BRK#5515 SHIFT_ISSUE:Bitwise shifts that are out of bounds for their data type. vmlinux get_bitmap(b=75) + 712 <net/netfilter/nf_conntrack_h323_asn1.c:0> vmlinux decode_seq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956 <net/netfilter/nf_conntrack_h323_asn1.c:592> vmlinux decode_choice(base=0xFFFFFFD0080370F0, level=23843636) + 1216 <net/netfilter/nf_conntrack_h323_asn1.c:814> vmlinux decode_seq(f=0xFFFFFFD0080371A8, level=134443500) + 812 <net/netfilter/nf_conntrack_h323_asn1.c:576> vmlinux decode_choice(base=0xFFFFFFD008037280, level=0) + 1216 <net/netfilter/nf_conntrack_h323_asn1.c:814> vmlinux DecodeRasMessage() + 304 <net/netfilter/nf_conntrack_h323_asn1.c:833> vmlinux ras_help() + 684 <net/netfilter/nf_conntrack_h323_main.c:1728> vmlinux nf_confirm() + 188 <net/netfilter/nf_conntrack_proto.c:137> Due to abnormal data in skb->data, the extension bitmap length exceeds 32 when decoding ras message then uses the length to make a shift operation. It will change into negative after several loop. UBSAN load could detect a negative shift as an undefined behaviour and reports exception. So we add the protection to avoid the length exceeding 32. Or else it will return out of range error and stop decoding.

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-787 Out-of-bounds Write

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
debian debian_linux

References

Advisories & Patches

https://git.kernel.org/stable/c/014a807f1cc9c9d5173c1cd935835553b00d211c https://git.kernel.org/stable/c/39001e3c42000e7c2038717af0d33c32319ad591 https://git.kernel.org/stable/c/4bafcc43baf7bcf93566394dbd15726b5b456b7a https://git.kernel.org/stable/c/767146637efc528b5e3d31297df115e85a2fd362 https://git.kernel.org/stable/c/80ee5054435a11c87c9a4f30f1ff750080c96416 https://git.kernel.org/stable/c/98db42191329c679f4ca52bec0b319689e1ad8cb https://git.kernel.org/stable/c/b3c0f553820516ad4b62a9390ecd28d6f73a7b13 https://git.kernel.org/stable/c/ccd1108b16ab572d9bf635586b0925635dbd6bbc https://git.kernel.org/stable/c/014a807f1cc9c9d5173c1cd935835553b00d211c https://git.kernel.org/stable/c/39001e3c42000e7c2038717af0d33c32319ad591 https://git.kernel.org/stable/c/4bafcc43baf7bcf93566394dbd15726b5b456b7a https://git.kernel.org/stable/c/767146637efc528b5e3d31297df115e85a2fd362 https://git.kernel.org/stable/c/80ee5054435a11c87c9a4f30f1ff750080c96416 https://git.kernel.org/stable/c/98db42191329c679f4ca52bec0b319689e1ad8cb https://git.kernel.org/stable/c/b3c0f553820516ad4b62a9390ecd28d6f73a7b13 https://git.kernel.org/stable/c/ccd1108b16ab572d9bf635586b0925635dbd6bbc

Frequently Asked Questions

What is CVE-2024-26851? +
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: Add protection for bmp length out of range UBSAN load reports an exception of BRK#5515 SHIFT_ISSUE:Bitwise shifts that are out of bounds for their data type. vmlinux get_bitmap(b=75) + 712 <net/netfilter/nf_conntrack_h323_asn1.c:0> vmlinux decode_seq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956 <net/netfilter/nf_conntrack_h323_asn1.c:592> vmlinux decode_choice(base=0xFFFFFFD0080370F0, level=23843636) + 1216 <net/netfilter/nf_conntrack_h323_asn1.c:814> vmlinux decode_seq(f=0xFFFFFFD0080371A8, level=134443500) + 812 <net/netfilter/nf_conntrack_h323_asn1.c:576> vmlinux decode_choice(base=0xFFFFFFD008037280, level=0) + 1216 <net/netfilter/nf_conntrack_h323_asn1.c:814> vmlinux DecodeRasMessage() + 304 <net/netfilter/nf_conntrack_h323_asn1.c:833> vmlinux ras_help() + 684 <net/netfilter/nf_conntrack_h323_main.c:1728> vmlinux nf_confirm() + 188 <net/netfilter/nf_conntrack_proto.c:137> Due to abnormal data in skb->data, the extension bitmap length exceeds 32 when decoding ras message then uses the length to make a shift operation. It will change into negative after several loop. UBSAN load could detect a negative shift as an undefined behaviour and reports exception. So we add the protection to avoid the length exceeding 32. Or else it will return out of range error and stop decoding. It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2024-26851? +
CVE-2024-26851 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2024-26851? +
CVE-2024-26851 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2024-26851? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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