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NVD / CVE Program· CNA Linux

CVE-2025-21629: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets

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: 0.43% (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 4.20, 5.11, 5.16; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes.
  • Severity is disputed: the assigning authority (CNA) scores it 8.2, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 4.20, 5.11, 5.16; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes 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: net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets The blamed commit disabled hardware offoad of IPv6 packets with extension headers on devices that advertise NETIF_F_IPV6_CSUM, based on the definition of that feature in skbuff.h: * * - %NETIF_F_IPV6_CSUM * - Driver (device) is only able to checksum plain * TCP or UDP packets over IPv6. These are specifically * unencapsulated packets of the form IPv6|TCP or * IPv6|UDP where the Next Header field in the IPv6 * header is either TCP or UDP. IPv6 extension headers * are not supported with this feature. This feature * cannot be set in features for a device with * NETIF_F_HW_CSUM also set. This feature is being * DEPRECATED (see below). The change causes skb_warn_bad_offload to fire for BIG TCP packets. [ 496.310233] WARNING: CPU: 13 PID: 23472 at net/core/dev.c:3129 skb_warn_bad_offload+0xc4/0xe0 [ 496.310297] ? skb_warn_bad_offload+0xc4/0xe0 [ 496.310300] skb_checksum_help+0x129/0x1f0 [ 496.310303] skb_csum_hwoffload_help+0x150/0x1b0 [ 496.310306] validate_xmit_skb+0x159/0x270 [ 496.310309] validate_xmit_skb_list+0x41/0x70 [ 496.310312] sch_direct_xmit+0x5c/0x250 [ 496.310317] __qdisc_run+0x388/0x620 BIG TCP introduced an IPV6_TLV_JUMBO IPv6 extension header to communicate packet length, as this is an IPv6 jumbogram. But, the feature is only enabled on devices that support BIG TCP TSO. The header is only present for PF_PACKET taps like tcpdump, and not transmitted by physical devices. For this specific case of extension headers that are not transmitted, return to the situation before the blamed commit and support hardware offload. ipv6_has_hopopt_jumbo() tests not only whether this header is present, but also that it is the only extension header before a terminal (L4) header.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jan 15, 2025
Updated
Aug 5, 2026
EPSS
0.4% · 37th percentile
CWE
—

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 · 0.4%

CNA vs NVD score

NVD
5.5
CNA · Linux
8.2
2.7 point gap

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

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

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  • 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 kernel4.19.323 and later · before 4.20
  • linux linux kernel5.4.285 and later · before 5.5
  • linux linux kernel5.10.229 and later · before 5.11
  • linux linux kernel5.15.171 and later · before 5.16
  • linux linux kernel6.1.116 and later · before 6.1.124
  • linux linux kernel6.6.60 and later · before 6.6.70
  • linux linux kernel6.11.7 and later · before 6.12
  • linux linux kernel6.12.1 and later · before 6.12.9
  • linux linux kernel6.12
  • linux linux kernel6.13

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

    • bcefc3cd7f592a70fcbbbfd7ad1fbc69172ea78b, 477b35d94a21530046fe91589960732fcf2b29ed, a27a5c40ee4cbe00294e2c76160de5f2589061ba, 9f605135a5c0fe614c2b15197b9ced1e217eca59, 705350fbd6ed4b5d89ee045fa57a0594a72b17d7, 6.12affected
    • a84978a9cda68f0afe3f01d476c68db21526baf1 and later · before ac9cfef69565021c9e1022a493a9c40b03e2caf9affected · git
    • c69bc67c1cb211aa390bea6e512bb01b1241fefb and later · before 95ccf006bbc8b59044313b8c309dcf29c546abd4affected · git
    • 04c20a9356f283da623903e81e7c6d5df7e4dc3c and later · before d3b7a9c7597b779039a51d7b34116fbe424bf2b7affected · git
    • 04c20a9356f283da623903e81e7c6d5df7e4dc3c and later · before 68e068cabd2c6c533ef934c2e5151609cf6ecc6daffected · git
    • 6.1.116 and later · before 6.1.124affected · semver
    • 6.6.60 and later · before 6.6.70affected · semver
    • 4.19.323 and later · before 4.20affected · semver
    • 5.4.285 and later · before 5.5affected · semver
    • 5.10.229 and later · before 5.11affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.124-16.1.124-1
Debian:13linuxbefore 6.12.9-16.12.9-1
openSUSE:Leap 15.6dtb-aarch64before 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-64kbbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-azurebefore 6.4.0-150600.8.40.16.4.0-150600.8.40.1
openSUSE:Leap 15.6kernel-debugbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-defaultbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-default-basebefore 6.4.0-150600.23.53.1.150600.12.24.16.4.0-150600.23.53.1.150600.12.24.1
openSUSE:Leap 15.6kernel-docsbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-kvmsmallbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-obs-buildbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-obs-qabefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-sourcebefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-source-azurebefore 6.4.0-150600.8.40.16.4.0-150600.8.40.1
openSUSE:Leap 15.6kernel-symsbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
openSUSE:Leap 15.6kernel-syms-azurebefore 6.4.0-150600.8.40.16.4.0-150600.8.40.1
openSUSE:Leap 15.6kernel-zfcpdumpbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_12before 1-150600.13.3.11-150600.13.3.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-64kbbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-defaultbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-default-basebefore 6.4.0-150600.23.53.1.150600.12.24.16.4.0-150600.23.53.1.150600.12.24.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-sourcebefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
SUSE:Linux Enterprise Module for Basesystem 15 SP6kernel-zfcpdumpbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1
SUSE:Linux Enterprise Module for Development Tools 15 SP6kernel-docsbefore 6.4.0-150600.23.53.16.4.0-150600.23.53.1

+11

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-2024-57900Jan 15, 2025 · ila: serialize calls to nf_register_net_hooks()
    31Monitor
  • ← EarlierCVE-2024-57903Jan 15, 2025 · net: restrict SO_REUSEPORT to inet sockets
    22Monitor
  • Later →CVE-2024-57857Jan 15, 2025 · RDMA/siw: Remove direct link to net_device
    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 Linux4.20Vendor (CNA)
Linux Linux5.11Vendor (CNA)
Linux Linux5.16Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux6.1.124Vendor (CNA)
Linux Linux6.12Vendor (CNA)
Linux Linux6.6.70Vendor (CNA)
Linux Linux68e068cabd2c6c533ef934c2e5151609cf6ecc6dVendor (CNA)
Linux Linux95ccf006bbc8b59044313b8c309dcf29c546abd4Vendor (CNA)
Linux Linuxac9cfef69565021c9e1022a493a9c40b03e2caf9Vendor (CNA)
Linux Linuxd3b7a9c7597b779039a51d7b34116fbe424bf2b7Vendor (CNA)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
debian:linux6.1.124-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-64kb6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-azure6.4.0-150600.8.40.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-debug6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default-base6.4.0-150600.23.53.1.150600.12.24.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-docs6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-kvmsmall6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-obs-build6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-obs-qa6.4.0-150600.23.53.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-source-azure6.4.0-150600.8.40.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-syms-azure6.4.0-150600.8.40.1 · openSUSE:Leap 15.6Package registry (OSV)
suse:kernel-64kb6.4.0-150600.23.53.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-azure6.4.0-150600.8.40.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-default6.4.0-150600.23.53.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-default-base6.4.0-150600.23.53.1.150600.12.24.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-docs6.4.0-150600.23.53.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP6Package registry (OSV)

+7

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).

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)

—

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. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records