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CVE Record

CVE-2024-49978: gso: fix udp gso fraglist segmentation after pull from frag_list

In the Linux kernel, the following vulnerability has been resolved: gso: fix udp gso fraglist segmentation after pull from frag_list Detect 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 UDP, this causes a NULL ptr deref in __udpv4_gso_segment_list_csum at udp_hdr(seg->next)->dest. 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.

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 UDP packet segmentation can crash the kernel when NAT or BPF processing changes packet-buffer geometry. The resulting denial of service affects availability; the supplied CVSS score is 7.5.

Executive priority

Treat as a high-priority availability issue for exposed network infrastructure, packet-processing hosts, and multi-tenant platforms. Confirm applicability promptly and schedule supported kernel updates; urgency is lower where affected UDP GSO and datapath conditions are absent.

Technical view

Modified SKB_GSO_FRAGLIST buffers may violate expected segment geometry after data is pulled from frag_list. UDP processing can then dereference a NULL pointer in __udpv4_gso_segment_list_csum. The kernel fix detects invalid head-buffer geometry and routes affected buffers through regular skb_segment processing.

Likely exposure

Exposure is most likely on affected Linux kernels handling UDP GSO fraglist traffic through datapath hooks such as NAT or bpf_skb_pull_data. The supplied affected-version data is ambiguous, so exact distribution package exposure requires vendor confirmation.

Exploitation context

The vector indicates network reachability without privileges or user interaction, with availability impact only. The bundle marks this CVE absent from KEV and provides no evidence of active exploitation or a public exploit.

Researcher notes

The failure depends on corrupted SKB_GSO_FRAGLIST geometry after optional datapath processing pulls data into the linear buffer. The fix preserves traffic by falling back to skb_segment rather than dropping malformed geometry. The bundle does not establish confidentiality impact, integrity impact, exploit reliability, or active attacks.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable stable fix.
  • Check distribution security guidance to map package versions to the referenced kernel fixes.
  • Prioritize externally reachable systems using UDP GSO with NAT or BPF datapath processing.
  • Use vendor-recommended temporary mitigations if immediate kernel replacement is unavailable.

Validation and detection

  • Inventory running kernel and distribution package versions across Linux systems.
  • Compare installed packages with vendor advisories and the referenced stable fixes.
  • Identify workloads using UDP GSO alongside NAT or BPF packet-processing hooks.
  • Review kernel logs for NULL dereferences involving __udpv4_gso_segment_list_csum.
  • Validate updated kernels in staging before production rollout.
Prepared
Confidence
medium
Sources
8

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-2024-49978 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
2ADP providers
7Source 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-2024-49978Attack 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
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9fd1ff5d2ac7181844735806b0a703c942365291, 9fd1ff5d2ac7181844735806b0a703c942365291, 9fd1ff5d2ac7181844735806b0a703c942365291, 9fd1ff5d2ac7181844735806b0a703c942365291, 9fd1ff5d2ac7181844735806b0a703c942365291unaffected
LinuxLinux5.6, 0, 6.1.113, 6.6.55, 6.10.14, 6.11.3, 6.12affected
Weakness

CWE details

No CWE listed

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