Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Linux Linux — netfilter: nf_conntrack_h323: Add protection for bmp length out of range
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U N N H 5.5 .0073 51.6 —
AFFECTED
Product Versions Fixed
Linux 5e35941d990123f155b02d5663e51a24f816b6f3 – —
Linux 2.6.17 – 4.19.310
TIMELINE
Feb 19 Reserved by Linux
Apr 17 Published (CNA: Linux)
Aug 4 RESCORED — CVE-2024-26851 (Linux). CVSS 7.5 → 5.5 (NVD).
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| February 19, 2024 | Reserved | Reserved by Linux |
| April 17, 2024 | Published | Published (CNA: Linux) |
| August 4, 2026 | RESCORED | RESCORED — CVE-2024-26851 (Linux). CVSS 7.5 → 5.5 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 5e35941d990123f155b02d5663e51a24f816b6f3 | — |
| Linux | Linux | — | 2.6.17 | 4.19.310 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2024-26851 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.