CVE
NLTK arbitrary file read in BllipParser
Only affects NLTK 3.10.0 through 3.10.3 when the optional bllipparser package is installed and an application passes an untrusted-derived model path to BllipParser. Fixed in 3.10.4.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 3.10.4
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. NLTK versions 3.10.0 through 3.10.3 are affected. The optional bllipparser package must be installed. The application must pass a model path derived from untrusted input to the BllipParser constructor or to from_unified_model_dir().
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 12/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
NLTK from 3.10.0 before 3.10.4 contains an arbitrary file read vulnerability in BllipParser that allows attackers to open files outside NLTK data roots by supplying unvalidated model paths. Attackers controlling parser_model, reranker_features, reranker_weights, or from_unified_model_dir() input can make the bllipparser C extension read sensitive files or block on FIFOs and devices.
Who should check
Teams running NLTK 3.10.0 through 3.10.3 with the optional bllipparser package, where BllipParser model paths come from untrusted input.
Read the source excerpt
“NLTK from 3.10.0 before 3.10.4 contains an arbitrary file read vulnerability in BllipParser”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity7/10CVSS 7.0
- No patch0/5No signal
What would change the score
- Would score about 62 if added to CISA KEV
- Would score about 57 if CISA's SSVC rates exploitation active
- Would score about 22 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
NLTK versions 3.10.0 through 3.10.3 are affected. The optional bllipparser package must be installed. The application must pass a model path derived from untrusted input to the BllipParser constructor or to from_unified_model_dir().Upgrade to a fixed version: 3.10.4.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126295 (NLTK 3.10.0 before 3.10.4 Arbitrary File Read via BllipParser Model Paths), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126295 (entry last updated 2026-11-13):
Affected:
- nltk nltk: from 3.10.0, fixed in 3.10.4
Fixed versions: 3.10.4.
Conditions (all must be true for the bug to be hit):
- NLTK versions 3.10.0 through 3.10.3 are affected. (source: https://www.vulncheck.com/advisories/nltk-3.10.0-before-3.10.4-arbitrary-file-read-via-bllipparser-model-paths)
- The optional bllipparser package must be installed. (source: https://github.com/nltk/nltk/security/advisories/GHSA-fg9w-wfp5-j933)
- The application must pass a model path derived from untrusted input to the BllipParser constructor or to from_unified_model_dir(). (source: https://github.com/nltk/nltk/security/advisories/GHSA-fg9w-wfp5-j933)
Setup: the bug needs a feature or setting that is off by default or uncommon. Check whether each asset has it on.
Attacker needs: local access, no login, no user action.
CISA KEV: CVE-2026-126295 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126295 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/nltk/nltk/security/advisories/GHSA-fg9w-wfp5-j933
- https://www.vulncheck.com/advisories/nltk-3.10.0-before-3.10.4-arbitrary-file-read-via-bllipparser-model-paths
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126295
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126295"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- nltk nltk
From 3.10.0 · fixed in 3.10.4
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126295
Is CVE-2026-126295 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A crafted model path can make NLTK open and read files of the attacker's choosing outside the NLTK data directories, such as local configuration or credential files readable by the process. It can also block on FIFOs and devices.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-126295?
nltk: from 3.10.0 before 3.10.4.Source: cve.now feed data
Am I affected, and how do I check?
NLTK versions 3.10.0 through 3.10.3 are affected, and only when the optional bllipparser package is installed and the application passes a model path derived from untrusted input to the BllipParser constructor or to from_unified_model_dir(). To check, look at the installed NLTK version and whether bllipparser is installed in the same environment.Source: vulncheck.com, github.com
How do I fix CVE-2026-126295?
Upgrade NLTK to version 3.10.4, which is the fixed version.Source: vulncheck.com, github.com