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NVD / CVE Program· CNA Linux

CVE-2026-98049: bpf: zero extend the result of an arena 32-bit cmpxchg

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1bb1be18263995b159cf5afad3a05500ba6d2a7b, 1c1b476d43a8b6c9bc04600369dd8cc39950d98e, 4814ed6406f3493bd554ad046da5f7fc04833571.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1bb1be18263995b159cf5afad3a05500ba6d2a7b, 1c1b476d43a8b6c9bc04600369dd8cc39950d98e, 4814ed6406f3493bd554ad046da5f7fc04833571 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: zero extend the result of an arena 32-bit cmpxchg bpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from BPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before bpf_opt_subreg_zext_lo32_rnd_hi32(). That pass emits an explicit zero extension for a 32-bit cmpxchg even when bpf_jit_needs_zext() is false. This is done because on some architectures 32-bit cmpxchg requires explicit zero extension for the dst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax if comparison is successful, while BPF semantics declare that each operation on a 32-bit register zero extends it's upper half. is_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena cmpxchg misses said zero extension adjustment. This patch adjusts is_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 21, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel6.10 and later · before 7.2.7
  • linux linux kernel7.3

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

    • 6.10affected
    • d503a04f8bc0c75dc9db9452d8cc79d748afb752 and later · before 1bb1be18263995b159cf5afad3a05500ba6d2a7baffected · git
    • d503a04f8bc0c75dc9db9452d8cc79d748afb752 and later · before 6bb6ae5ab1beffda51dabf41612f501d07f10fc6affected · git
    • d503a04f8bc0c75dc9db9452d8cc79d748afb752 and later · before 1c1b476d43a8b6c9bc04600369dd8cc39950d98eaffected · git
    • d503a04f8bc0c75dc9db9452d8cc79d748afb752 and later · before 4814ed6406f3493bd554ad046da5f7fc04833571affected · git
    • before 6.10not affected · semver
    • 6.12.114 and later · up to and including 6.12.*not affected · semver
    • 6.18.57 and later · up to and including 6.18.*not affected · semver
    • 7.2.7 and later · up to and including 7.2.*not affected · semver
    • 7.3 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.115-26.12.115-2
Debian:14linuxbefore 7.2.7-17.2.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-17523Jul 27, 2026 · can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet
    31Monitor
  • ← EarlierCVE-2026-0291Aug 13, 2026 · Prisma Access Agent: Authenticated Limited File Deletion on Linux
    4Monitor
  • Later →CVE-2026-98050Sep 25, 2026 · mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context
    30Monitor

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 Linux1bb1be18263995b159cf5afad3a05500ba6d2a7bVendor (CNA)
Linux Linux1c1b476d43a8b6c9bc04600369dd8cc39950d98eVendor (CNA)
Linux Linux4814ed6406f3493bd554ad046da5f7fc04833571Vendor (CNA)
Linux Linux6bb6ae5ab1beffda51dabf41612f501d07f10fc6Vendor (CNA)
debian:linux6.12.115-2 · Debian:13Package registry (OSV)
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.

  • CVE-2026-5305393 days apartiommu/amd: Fix clone_alias() to use the original device's devid
    35Monitor
  • CVE-2026-6392668 days apartbpf: sockmap: fix tail fragment offset in bpf_msg_push_data
    33Monitor
  • CVE-2026-981430 days apartaccel: ethosu: Don't read the U65 rounding mode as a storage mode
    31Monitor
  • CVE-2026-5313392 days apartRDMA/umem: Fix truncation for block sizes >= 4G
    31Monitor
  • CVE-2026-980950 days apartaf_packet: Don't cast tpacket_hdr.tp_len to int in tpacket_parse_header().
    22Monitor

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

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-681 · Incorrect Conversion between Numeric Types

CVSS vector

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

nvd-primary

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. CVSS— → 5.5
  2. Severity— → medium
  3. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

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

All records