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CVE Record

CVE-2026-53671: PREVAIL: Context-write no-op in do_mem_store allows unsafe eBPF programs to pass verification

PREVAIL is a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer. Prior to version 0.2.4, the abstract transformer in prevail treats writes through a T_CTX-typed base register as a silent no-op: do_mem_store in src/crab/ebpf_transformer.cpp only models T_STACK stores, and the checker's T_CTX bounds arm never tests AccessType::write. An attacker can craft an eBPF program that overwrites a context field (e.g., ctx->data), reload that field typed as T_PACKET, and dereference an attacker-controlled address — and prevail will report the program as safe. This issue has been patched in version 0.2.4.

CriticalCVSS 9.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

PREVAIL versions before 0.2.4 can incorrectly approve a malicious eBPF program as safe. The flaw could let an attacker replace a trusted context value with an attacker-controlled address, then access that address. Consequences include serious confidentiality and integrity impact wherever PREVAIL’s verification decision is trusted.

Executive priority

Treat this as an urgent remediation for environments that accept untrusted eBPF programs or rely on PREVAIL as a security boundary. Upgrade promptly and confirm downstream dependencies. Systems without PREVAIL, or already running 0.2.4 or later, are not identified as affected by the supplied evidence.

Technical view

PREVAIL’s abstract transformer models memory stores only for stack-typed bases. Stores through a T_CTX register become no-ops, while context bounds checking does not test write access. A program can overwrite a context field, reload it as T_PACKET, and dereference an attacker-controlled address despite verification. Version 0.2.4 corrects the issue.

Likely exposure

Exposure is limited to systems using vbpf PREVAIL below 0.2.4, particularly where its approval permits untrusted eBPF programs to execute. The supplied sources do not identify specific downstream products, deployments, or configuration prerequisites. Organizations should inventory direct and transitive PREVAIL use before assuming exposure.

Exploitation context

The vulnerability is remotely reachable under the supplied CVSS assessment and requires neither privileges nor user interaction. However, the source bundle provides no evidence of active exploitation, and the CVE is not listed as KEV. Practical risk depends on whether attackers can submit eBPF programs to a workflow relying on PREVAIL’s verdict.

Researcher notes

The failure is a verifier soundness bug caused by inconsistent modeling of context writes and subsequent typed reloads. CWE-682 applies. The published fix is commit de65234f67d2608b54d12571edb585ead224363c and release 0.2.4. No public exploitation evidence or named affected downstream integrations appears in the supplied bundle.

Mitigation direction

  • Upgrade PREVAIL to version 0.2.4 or later.
  • Identify services and pipelines that trust PREVAIL verification results.
  • Restrict untrusted eBPF submission until affected verifiers are upgraded.
  • Review vendor guidance for downstream products embedding PREVAIL.

Validation and detection

  • Confirm deployed and transitive PREVAIL versions are 0.2.4 or later.
  • Verify all verifier hosts, containers, and build artifacts received the update.
  • Test that writes through context-typed registers are rejected or safely modeled.
  • Review logs for untrusted eBPF submissions accepted by vulnerable PREVAIL versions.
Prepared
Confidence
high
Sources
5

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

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cwe · low confidence lookup

CWE-682: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-53671 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.3 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

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
0ADP providers
4Source links

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
9.3CVSS 4.0CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N——GitHub_M

Vulnerability scoring details

Base CVSS 4.0 score

9.3Critical
CVSS 4.0 vector shape for CVE-2026-53671Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
vbpfprevail< 0.2.4Listed
Weakness

CWE details

CWE-682

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

CWE-682 · source CWE mapping

Incorrect Calculation

Incorrect Calculation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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