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CVE Record

CVE-2026-43500: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec(). Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-43500 is a high-severity Linux kernel memory-safety flaw in rxrpc packet handling. A local user could potentially abuse externally shared packet fragments during cryptographic processing, risking kernel memory corruption with confidentiality, integrity, and availability impact.

Executive priority

Treat as a high-priority kernel update for shared Linux infrastructure. It is not described as remotely exploitable in the supplied evidence, but local privilege and full CIA impact make delayed patching risky on multi-tenant systems.

Technical view

rxrpc DATA and RESPONSE handlers only linearized cloned skbs before security operations. Non-cloned skbs with shared paged fragments could enter in-place decryption and bind externally owned pages into crypto scatter-gather lists. The fix expands unsharing to frag lists and shared frags.

Likely exposure

Exposure is most relevant to Linux systems running affected kernels where untrusted local users can interact with paths that reach rxrpc over UDP. Exact distro exposure needs vendor kernel mapping because the bundle lists upstream commits and Red Hat tracking sources.

Exploitation context

The bundle includes a GitHub reference tagged as exploit, but does not show CISA KEV listing or confirmed active exploitation. The CVSS vector is local, low complexity, low privilege, and no user interaction.

Researcher notes

Focus validation on rxrpc skb handling changes: unshare checks now include skb_has_frag_list() and skb_has_shared_frag(). Avoid assuming exact affected distribution ranges from upstream hashes alone; use vendor advisories for shipped kernel status.

Mitigation direction

  • Apply vendor kernel updates that include the referenced upstream rxrpc fixes.
  • Check Red Hat and other distribution advisories for backported fixed kernel builds.
  • Prioritize multi-user Linux hosts and systems exposed to untrusted local workloads.
  • If updates are unavailable, follow vendor guidance for reducing rxrpc-related exposure.

Validation and detection

  • Inventory Linux kernel versions and distribution package release levels.
  • Map installed kernels against vendor advisories for CVE-2026-43500.
  • Confirm fixed upstream commits or distro backports are present.
  • Review whether untrusted local users or workloads exist on affected systems.
Prepared
Confidence
medium
Sources
11

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-123: Exact CWE lookup

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cwe · low confidence lookup

CWE-787: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-43500 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

3CVSS vectors
5Timeline events
2ADP providers
10Source links

SSVC decision data

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

CVSS vector scores

3 official scores

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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9CISA-ADP
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-43500Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. ADP timelineredhat-SADP

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
redhat-SADPkernel: "Dirty Frag" RxRPC variant is a new universal Local Privilege Escalation (LPE) vulnerability in the Linux kernel
other:Red Hat severity ratingcvssV3_1
  • 2026-05-11T00:00:00.000Z: Reported to Red Hat.
  • 2026-05-11T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxd0d5c0cd1e711c98703f3544c1e6fc1372898de5, d0d5c0cd1e711c98703f3544c1e6fc1372898de5, d0d5c0cd1e711c98703f3544c1e6fc1372898de5, d0d5c0cd1e711c98703f3544c1e6fc1372898de5, d0d5c0cd1e711c98703f3544c1e6fc1372898de5unaffected
LinuxLinux5.3, 0, 6.6.140, 6.12.88, 6.18.29, 7.0.6, 7.1affected
Weakness

CWE details

CWE-123CWE-787

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-123 · source CWE mapping

Write-what-where Condition

Write-what-where Condition represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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