Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 0.41% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-65915High confidence
NLTK before 3.10.0 Arbitrary File Read via FileSystemPathPointer
nltk · nltk
Official source article: GitHub GHSA-72R2-7MFR-5XR9 ↗. Check the applicable product and release in the original source.
7.1HighCVSS 4.0
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 24 Aug 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs nltk nltk and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 14 affected or under-investigation product states without a fixed product state in the same current advisory
- Debian Security Tracker: 2 affected package states with no published fix
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 2 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | nltk | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | nltk | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | nltk | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.10.0-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | nltk | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.10.0-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · esm-apps | nltk | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| pipnltk | <= 3.9.3 | 3.10.0 | GitHub advisory ↗upstream repository advisory · 8 Sep 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-65915 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitynltk: NLTK: Arbitrary file read due to logic bug in FileSystemPathPointer
The vendor explicitly identifies these products as affected by this CVE.
- exploit-intelligence-tech-preview/vulnerability-analysis-rhel9 as a component of Exploit Intelligence
- lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core
- lightspeed-core/rag-tool-cpu-rhel9 as a component of Lightspeed Core
- lightspeed-core/rag-tool-cuda-12.9-rhel9 as a component of Lightspeed Core
- openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9 as a component of OpenShift Lightspeed
- openshift-lightspeed/lightspeed-ocp-rag-rhel9 as a component of OpenShift Lightspeed
- ansible-automation-platform-25/lightspeed-chatbot-rhel8 as a component of Red Hat Ansible Automation Platform 2
- rhoai/odh-llama-stack-core-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-ogx-core-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-ta-lmes-job-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- Summary
- A flaw was found in NLTK. A logic bug in the `FileSystemPathPointer.open()` function allows the sandbox validation check to be bypassed. A remote attacker can exploit this by providing specially crafted `file://` Uniform Resource Locators (URLs) to `nltk.data.load()`. This enables the attacker to read arbitrary files on the system, potentially leading to the disclosure of sensitive information such as credentials and configuration files.
- Remediation
- Mitigation for this issue involves ensuring that applications utilizing the NLTK library do not process untrusted `file://` URLs through `nltk.data.load()`. Implement input validation and sanitization for any data passed to NLTK functions that could resolve file paths. Additionally, running applications that use NLTK with the principle of least privilege can limit the impact of successful exploitation by restricting access to sensitive files.
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.
What
NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.
Why
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may obtain information outside the intended access boundary.
What
NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.
Why
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may obtain information outside the intended access boundary.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- a network path → Improper Access Control → obtain information outside the intended access boundary
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-284 ↗
CWE-284: Improper Access Control. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- exploit-intelligence-tech-preview/vulnerability-analysis-rhel9 as a component of Exploit Intelligence
- lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core
- lightspeed-core/rag-tool-cpu-rhel9 as a component of Lightspeed Core
- lightspeed-core/rag-tool-cuda-12.9-rhel9 as a component of Lightspeed Core
- openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9 as a component of OpenShift Lightspeed
- openshift-lightspeed/lightspeed-ocp-rag-rhel9 as a component of OpenShift Lightspeed
- ansible-automation-platform-25/lightspeed-chatbot-rhel8 as a component of Red Hat Ansible Automation Platform 2
- rhoai/odh-llama-stack-core-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-ogx-core-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-ta-lmes-job-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-trustyai-nemo-guardrails-server-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- Fixed
- nltk: 3.10.0
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Mitigation for this issue involves ensuring that applications utilizing the NLTK library do not process untrusted `file://` URLs through `nltk.data.load()`. Implement input validation and sanitization for any data passed to NLTK functions that could resolve file paths. Additionally, running applications that use NLTK with the principle of least privilege can limit the impact of successful exploitation by restricting access to sensitive files.
Official vendor articles1 stored document
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- FileSystemPathPointer.open() sandbox check is dead code — arbitrary file read via file:// protocol · Advisory · nltk/nltk · GitHub →Original publisher ↗Searchable text snapshot · Captured 27 Sep 2026nltk / nltk Public Notifications You must be signed in to change notification settings Fork 3k Star 14.7k Code Issues 217 Pull requests 44 Discussions Actions Projects Wiki Security and quality 37 Insights Additional navigation options Code Issues Pull requests Discussions Actions Projects Wiki Secur
04
Evidence and provenance
Published 22 Aug 2026 · Last source change 24 Aug 2026, 19:20 UTC · CWE-284 · Improper Access Control
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-23
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-64309
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: github.com/GHSA-72r2-7mfr-5xr9.github.com ↗
- Before
- remediation: github.com/GHSA-72r2-7mfr-5xr9
- After
- remediation: github.com/GHSA-72r2-7mfr-5xr9 · vendor advisory: github.com/GHSA-72r2-7mfr-5xr9
- Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.github.com ↗
- Before
- Public exploit reference
- After
- Public exploit reference
- Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.CVE.org ↗
- Before
- No public exploit
- After
- Public exploit reference
- ENISA EUVD mappingEUVD-2026-64309 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-64309"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.