VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-98042: Linux kernel · bpf: Don't resurrect a scalar id dropped by collect_linked_regs()

Affects Linux kernelSource CVE Database V5

Not known to be exploited : upgrade to e821ff19b8ef08255ff8d8234774ed814637e9bf or 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e821ff19b8ef08255ff8d8234774ed814637e9bf, 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to e821ff19b8ef08255ff8d8234774ed814637e9bf or 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ ec1d77cb0ee98249142dcd0376d76e7a48ba0b31, < e821ff19b8ef08255ff8d8234774ed814637e9bf	Fixed in e821ff19b8ef08255ff8d8234774ed814637e9bf
LinuxLinux	Affected ≥ ec1d77cb0ee98249142dcd0376d76e7a48ba0b31, < 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b	Fixed in 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b
LinuxLinux	Affected =7.1	Fixed in–

AI-suggested

The vulnerability has been fixed in the Linux kernel commits e821ff19b8ef08255ff8d8234774ed814637e9bf and 73a98f96811e2cb0f4210b1caa8cb322f92f2a2b. Users should update to these fixed versions or later to remediate the issue. No additional mitigation actions are indicated.

Description

A vulnerability in the Linux kernel's BPF subsystem involves improper handling of scalar register IDs during linked register collection, which could lead to incorrect register state synchronization. The issue was fixed by changing the order of linked register collection to prevent resurrection of dropped scalar IDs. This fix addresses potential inaccuracies in register state tracking within BPF programs.

Impact

This vulnerability affects the internal consistency of register state tracking in the Linux kernel's BPF subsystem. While no direct exploitation or impact on system security is described, the flaw could cause incorrect behavior in BPF programs relying on precise register state, potentially leading to logic errors or unexpected results in kernel-level packet filtering or tracing.

Summary

The Linux kernel vulnerability CVE-2026-98042 concerns the BPF subsystem's handling of scalar register IDs in the function collect_linked_regs(). The function records linked registers but drops scalar IDs that do not fit, including compared registers. However, the snapshots of compared registers are taken before linked registers are collected, causing a mismatch when sync_linked_regs() adjusts register ranges beyond what bpf_bt_sync_linked_regs() can propagate. The fix involves collecting linked registers before taking snapshots, preventing resurrection of dropped scalar IDs and ensuring accurate register state synchronization in BPF jump history.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 12:53 UTC

Technical details

References

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