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CVE Record

CVE-2024-49979: net: gso: fix tcp fraglist segmentation after pull from frag_list

In the Linux kernel, the following vulnerability has been resolved: net: gso: fix tcp fraglist segmentation after pull from frag_list Detect tcp gso fraglist skbs with corrupted geometry (see below) and pass these to skb_segment instead of skb_segment_list, as the first can segment them correctly. Valid SKB_GSO_FRAGLIST skbs - consist of two or more segments - the head_skb holds the protocol headers plus first gso_size - one or more frag_list skbs hold exactly one segment - all but the last must be gso_size Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can modify these skbs, breaking these invariants. In extreme cases they pull all data into skb linear. For TCP, this causes a NULL ptr deref in __tcpv4_gso_segment_list_csum at tcp_hdr(seg->next). Detect invalid geometry due to pull, by checking head_skb size. Don't just drop, as this may blackhole a destination. Convert to be able to pass to regular skb_segment. Approach and description based on a patch by Willem de Bruijn.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in Linux TCP packet segmentation can crash the kernel when NAT, BPF, or similar processing changes specially structured network buffers. Successful triggering affects availability rather than data confidentiality or integrity. Exposed network services using affected kernels and relevant packet-processing hooks deserve prompt review.

Executive priority

Treat as a high-priority availability issue for exposed Linux gateways and hosts with relevant network hooks. Patch through supported vendor channels promptly, prioritizing critical traffic paths. Broader emergency action is not supported by the supplied evidence because active exploitation is unconfirmed.

Technical view

TCP GSO fraglist buffers can retain invalid geometry after a datapath hook pulls data from the fragment list. The optimized segmentation path then may dereference a null next-segment pointer in __tcpv4_gso_segment_list_csum. The kernel fix detects malformed geometry and routes the buffer through regular skb_segment processing.

Likely exposure

The source identifies Linux 6.10-era and 6.11-era releases, with listed boundaries including 6.10.14 and 6.11.3. The supplied version representation is ambiguous, so exact exposure should be established through distribution advisories and fix-commit mapping. Risk is most relevant where NAT, BPF, or other hooks modify TCP GSO fraglist buffers.

Exploitation context

The CVSS assessment is 7.5 with network reachability, low complexity, no privileges, and availability-only impact. The supplied record is not in CISA KEV and provides no evidence of active exploitation or a public exploit. Practical triggering depends on affected packet geometry and datapath processing conditions.

Researcher notes

The safety change validates the head buffer's size before selecting skb_segment_list and falls back to skb_segment for altered geometry. This avoids dropping traffic and potential destination blackholing. The bundle contains several stable-tree commits, indicating backports, but its flattened affected-version data does not reliably communicate precise inclusive and exclusive boundaries.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable referenced stable fix.
  • Confirm distribution backports because package versions may not match upstream kernel numbering.
  • Prioritize internet-facing systems using NAT, BPF, or substantial network packet processing.
  • Review vendor guidance before changing datapath features as a temporary risk reduction.

Validation and detection

  • Inventory running kernel versions across hosts, appliances, containers' hosts, and network gateways.
  • Map each distribution kernel to the referenced upstream fix commits or vendor advisories.
  • Identify systems using NAT, BPF programs, or other packet-modifying hooks.
  • Review kernel crash records for null dereferences involving __tcpv4_gso_segment_list_csum.
  • After updating, verify the fixed kernel is running rather than merely installed.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2024-49979 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
1ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2024-49979Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxc2ea8cab368b9f25b5937a7f07ab1a66e90b8064, 1f2b859225eb8d1ec974214ce4a581f8c528ae57, bee88cd5bd83d40b8aec4d6cb729378f707f6197, bee88cd5bd83d40b8aec4d6cb729378f707f6197, bee88cd5bd83d40b8aec4d6cb729378f707f6197unaffected
LinuxLinux6.10, 0, 6.10.14, 6.11.3, 6.12affected
Weakness

CWE details

No CWE listed

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