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CVE Record

CVE-2026-2297: SourcelessFileLoader does not use io.open_code()

The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.

MediumCVSS 5.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CPython can load certain legacy bytecode-only files without triggering the expected security audit event. Organizations relying on that event to inspect or block code loading may have a control gap. The issue requires local, low-privileged access and a prerequisite condition, limiting broad remote risk.

Executive priority

Treat this as a targeted integrity-control issue, not an emergency remote-compromise event. Prioritize systems that use Python audit hooks as enforcement boundaries or permit local users to influence import locations. Schedule vendor-approved updates through normal vulnerability remediation timelines, escalating exposed security-sensitive runtimes.

Technical view

SourcelessFileLoader reads legacy .pyc files through FileLoader without using io.open_code(). Consequently, sys.audit handlers associated with that operation do not fire. This can bypass audit-based enforcement or monitoring for affected imports; the CVSS 4.0 assessment indicates high integrity impact but no confidentiality or availability impact.

Likely exposure

Exposure is most likely where a listed CPython version loads legacy sourceless .pyc files and security controls depend on io.open_code audit events. The bundle identifies specific versions, not complete affected ranges, so vendor or distributor backport status must be checked.

Exploitation context

The bundle marks this CVE as absent from KEV and provides no cited evidence of active exploitation. The CVSS vector requires local access, low privileges, and a prerequisite condition. Practical impact depends on an attacker influencing imported .pyc content and the environment relying on the missing audit event.

Researcher notes

The supplied affected data names 0, 3.11.0, 3.12.0, 3.13.0, 3.14.0, and 3.15.0a1 while declaring other versions unaffected by default. It supplies no version ranges or fixed release numbers. Multiple upstream commits are identified as patches; downstream package status remains unspecified.

Mitigation direction

  • Review the CPython patch commits and obtain an updated or backported package from the relevant vendor or distributor.
  • Restrict low-privileged users from modifying application bytecode files and directories searched during imports.
  • Avoid untrusted legacy sourceless .pyc files where operationally feasible.
  • Do not treat audit-event monitoring as the only control protecting executable Python import paths.

Validation and detection

  • Inventory CPython deployments matching the specifically listed versions.
  • Identify applications using sys.audit or io.open_code events for monitoring or enforcement.
  • Confirm whether workloads load legacy sourceless .pyc files from writable or untrusted locations.
  • In safe staging, verify the expected audit event occurs after applying the vendor-approved fix.
  • Confirm package backport status against the referenced CPython changes.
Prepared
Confidence
high
Sources
10

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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cwe · low confidence lookup

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cve · low confidence lookup

CVE-2026-2297 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.7 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/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
2ADP providers
9Source 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
5.7CVSS 4.0MediumCVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N——PSF

Vulnerability scoring details

Base CVSS 4.0 score

5.7Medium
CVSS 4.0 vector shape for CVE-2026-2297Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/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.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Python Software FoundationCPython0, 3.11.0, 3.12.0, 3.13.0, 3.14.0, 3.15.0a1unaffected
Weakness

CWE details

CWE-668

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CWE-668 · source CWE mapping

Exposure of Resource to Wrong Sphere

Exposure of Resource to Wrong Sphere represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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