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NVD / CVE Program· CNA Linux

CVE-2026-98044: bpf: Reject legacy packet loads from callbacks

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 3484a99303912db62428494a9061212049027e57, 5.11, 5.16; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3484a99303912db62428494a9061212049027e57, 5.11, 5.16; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject legacy packet loads from callbacks check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a subprogram as an implicit return with R0 set to zero. It calls prepare_func_exit() to explore this synthesized path. When the load is reached directly from a synchronous callback, prepare_func_exit() enforces the callback return contract and marks R0 precise. R0 is not derived from a real instruction on this path, so precision backtracking reaches the callback call with R0 still requested and triggers the "callback unexpected regs" verifier bug. A privileged program loader can therefore cause a verifier warning and an -EFAULT BPF_PROG_LOAD. These legacy packet-load instructions are deprecated. Reject them from callbacks rather than complicating their implicit-return model. Check all active frames before constructing the implicit return so nested static subprograms cannot hide the callback context. Global functions are verified independently with a fresh frame zero, so an active-frame check cannot identify a global function called from a callback. Also check the complete subprogram call graph during stack-depth validation and reject a function containing a legacy load when any caller is a callback. This covers global and static descendants without making has_ld_abs transitive, preserving its per-function BTF return-type check. Ordinary uses outside callbacks remain supported.

—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 928d354ae3557e8f755a227e67be88034eb3cd7f, 8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe, de1055e7f9e67af32b1f3376066272b04e5223c0, 37ad2bb11e9de92cb7b94548705eeedd87f7d392, d846d83bdacbd8f14fc45c63b8c1d22608452e1c, 7.1affected
    • 8674e2db06cff6b50f2216eed9a761d15425bb34 and later · before cebda2a2bb4183550eae9dcf888c16407b4fffdaaffected · git
    • ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337 and later · before 3484a99303912db62428494a9061212049027e57affected · git
    • ee861486e377edc55361c08dcbceab3f6b6577bd and later · before bc489c0c9b8c86bd7fac42cfd1bb152f042fca56affected · git
    • ee861486e377edc55361c08dcbceab3f6b6577bd and later · before e7d28823c662128caae63f14e16bd394916c139baffected · git
    • 6.12.101 and later · before 6.12.114affected · semver
    • 6.18.42 and later · before 6.18.53affected · semver
    • 5.10.265 and later · before 5.11affected · semver
    • 5.15.216 and later · before 5.16affected · semver
    • 6.1.183 and later · before 6.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.2.7-17.2.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-98042Sep 25, 2026 · bpf: Don't resurrect a scalar id dropped by collect_linked_regs()
    0Monitor
  • ← EarlierCVE-2026-98043Sep 25, 2026 · bpf: Don't infer non-NULL from a pointer with an unbounded offset
    0Monitor
  • Later →CVE-2026-98045Sep 25, 2026 · bpf: Mark faultable stack helpers as sleepable
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux3484a99303912db62428494a9061212049027e57Vendor (CNA)
Linux Linux5.11Vendor (CNA)
Linux Linux5.16Vendor (CNA)
Linux Linux6.12.114Vendor (CNA)
Linux Linux6.18.53Vendor (CNA)
Linux Linux6.2Vendor (CNA)
Linux Linux6.7Vendor (CNA)
Linux Linux7.1Vendor (CNA)
Linux Linuxbc489c0c9b8c86bd7fac42cfd1bb152f042fca56Vendor (CNA)
Linux Linuxcebda2a2bb4183550eae9dcf888c16407b4fffdaVendor (CNA)
Linux Linuxe7d28823c662128caae63f14e16bd394916c139bVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
debian:linux7.2.7-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records