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NVD / CVE Program· CNA Linux

CVE-2026-52999: netfilter: nfnetlink_osf: fix out-of-bounds read on option matching

Noroxi assessment

Priority: Monitor (action score 36/100)

  • 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: 0.59% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 0145548346c4a30981a870a8ca00eac46ba27e85, 1c136f2c44a5913646bac85303612fd0825197a0, 1e19a07291bb8682c14c39a64725a3ae54ab8ccc; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0145548346c4a30981a870a8ca00eac46ba27e85, 1c136f2c44a5913646bac85303612fd0825197a0, 1e19a07291bb8682c14c39a64725a3ae54ab8ccc; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1 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: netfilter: nfnetlink_osf: fix out-of-bounds read on option matching In nf_osf_match(), the nf_osf_hdr_ctx structure is initialized once and passed by reference to nf_osf_match_one() for each fingerprint checked. During TCP option parsing, nf_osf_match_one() advances the shared ctx->optp pointer. If a fingerprint perfectly matches, the function returns early without restoring ctx->optp to its initial state. If the user has configured NF_OSF_LOGLEVEL_ALL, the loop continues to the next fingerprint. However, because ctx->optp was not restored, the next call to nf_osf_match_one() starts parsing from the end of the options buffer. This causes subsequent matches to read garbage data and fail immediately, making it impossible to log more than one match or logging incorrect matches. Instead of using a shared ctx->optp pointer, pass the context as a constant pointer and use a local pointer (optp) for TCP option traversal. This makes nf_osf_match_one() strictly stateless from the caller's perspective, ensuring every fingerprint check starts at the correct option offset.

CriticalCVSS 9.1 · v3.1—No exploit Fix available
Published
Jun 24, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 48th percentile

Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-52999

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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 kernel4.19.26 and later · before 4.20
  • linux linux kernel4.20.13 and later · before 5.0
  • linux linux kernel5.0.1 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.141
  • linux linux kernel6.7 and later · before 6.12.91
  • linux linux kernel6.13 and later · before 6.18.33
  • linux linux kernel6.19 and later · before 7.0.10
  • linux linux kernel5.0

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

    • 0c1054e0e5fdef2369fb089e94def978bd209e1f, 8316b60582facd4068fb0916c4db2418c21b7174, 5.0affected
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 0145548346c4a30981a870a8ca00eac46ba27e85affected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 1c136f2c44a5913646bac85303612fd0825197a0affected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 1e19a07291bb8682c14c39a64725a3ae54ab8cccaffected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 32e50f92c7cf3f4eba29622179a5fcdc2aebab41affected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 70a3f31d25cf2ec9d4ddfa408120171ead955623affected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before 21883587593d7c8bb519a79460a0b5bc5ffbdabdaffected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before edb78a142d2e5948e63647c0646aa7e7886935f0affected · git
    • 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b and later · before f5ca450087c3baf3651055e7a6de92600f827af3affected · git
    • 4.19.26 and later · before 4.20affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.10-17.0.10-1

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-2026-52995Jun 24, 2026 · net/rds: zero per-item info buffer before handing it to visitors
    22Monitor
  • ← EarlierCVE-2026-52998Jun 24, 2026 · netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check
    30Monitor
  • Later →CVE-2026-53000Jun 24, 2026 · netfilter: nat: use kfree_rcu to release ops
    31Monitor

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 Linux0145548346c4a30981a870a8ca00eac46ba27e85Vendor (CNA)
Linux Linux1c136f2c44a5913646bac85303612fd0825197a0Vendor (CNA)
Linux Linux1e19a07291bb8682c14c39a64725a3ae54ab8cccVendor (CNA)
Linux Linux21883587593d7c8bb519a79460a0b5bc5ffbdabdVendor (CNA)
Linux Linux32e50f92c7cf3f4eba29622179a5fcdc2aebab41Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux4.21Vendor (CNA)
Linux Linux70a3f31d25cf2ec9d4ddfa408120171ead955623Vendor (CNA)
Linux Linuxedb78a142d2e5948e63647c0646aa7e7886935f0Vendor (CNA)
Linux Linuxf5ca450087c3baf3651055e7a6de92600f827af3Vendor (CNA)
azl3 kernel 6.6.139.1-1 on Azure Linux 3.06.6.143.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.176-1 · Debian:12Package 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.

No history yet (it accumulates with the daily EPSS job).

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

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

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

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-secondary

Attack context

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

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (9 more)

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

All records