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NVD / CVE Program· CNA Linux

CVE-2026-72502: tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.71% (FIRST EPSS); higher than 53.9% of all records.
  • 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 21f69ac1879bb970588d5e7c12a96e6542f7c1a7, 2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22, 560b33b434e922ef97f9ff23aa2e909ef7aacd5c.

Low priority for now. Upgrade to Linux Linux 21f69ac1879bb970588d5e7c12a96e6542f7c1a7, 2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22, 560b33b434e922ef97f9ff23aa2e909ef7aacd5c 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: tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF) When MTU is large, ip6_default_advmss() can return IPV6_MAXPLEN (65535). This is interpreted by TCP as mss_clamp, allowing the MSS to reach 65535. However, 0xFFFF is also used as a magic value GSO_BY_FRAGS in the kernel. If a TCP packet with gso_size=0xFFFF is passed to skb_segment(), it will be mistakenly treated as GSO_BY_FRAGS, leading to a NULL pointer dereference because local TCP packets do not use frag_list. Fix this by returning min(IPV6_MAXPLEN, GSO_BY_FRAGS - 1) (65534) from ip6_default_advmss() when MTU is large. Also update the stale comment in ip6_default_advmss() which suggested that IPV6_MAXPLEN is returned to mean "any MSS".

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 16, 2026
EPSS
0.7% · 53th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
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-2026-72502

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.

—

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

    • 4.8affected
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before 560b33b434e922ef97f9ff23aa2e909ef7aacd5caffected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before 21f69ac1879bb970588d5e7c12a96e6542f7c1a7affected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before c0db3dc2ac323b6c4b76adede3b355a9daa6dea8affected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before 572fff10819dfc359298d1f774839e76a4d96f93affected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before 8e6214a530c03e341dc1b0a846c8f2b716b3551aaffected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before d774cdbda6634a78d0f2baf201ee5a8c57f3bc0eaffected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before a210791f33345aa87187f7d7a9f3b9b7f4a28e6daffected · git
    • 3953c46c3ac7eef31a9935427371c6f54a22f1ba and later · before 2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22affected · git
    • before 4.8not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

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-2026-72500Aug 15, 2026 · RDMA/bnxt_re: Free SRQ toggle page after firmware teardown
    35Monitor
  • ← EarlierCVE-2026-72501Aug 15, 2026 · RDMA/bnxt_re: Initialize dpi variable to zero
    0Monitor
  • Later →CVE-2026-74255Aug 15, 2026 · tipc: fix UAF in tipc_l2_send_msg()
    39Monitor

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 Linux21f69ac1879bb970588d5e7c12a96e6542f7c1a7Vendor (CNA)
Linux Linux2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22Vendor (CNA)
Linux Linux560b33b434e922ef97f9ff23aa2e909ef7aacd5cVendor (CNA)
Linux Linux572fff10819dfc359298d1f774839e76a4d96f93Vendor (CNA)
Linux Linux8e6214a530c03e341dc1b0a846c8f2b716b3551aVendor (CNA)
Linux Linuxa210791f33345aa87187f7d7a9f3b9b7f4a28e6dVendor (CNA)
Linux Linuxc0db3dc2ac323b6c4b76adede3b355a9daa6dea8Vendor (CNA)
Linux Linuxd774cdbda6634a78d0f2baf201ee5a8c57f3bc0eVendor (CNA)
debian:linux6.1.180-1 · 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.

EPSS, last 120 days+1% in 7 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).

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
none
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
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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

Change log

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

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

References

Show all references (7 more)

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

All records