Bug 2521336 (CVE-2026-63312)

Summary: CVE-2026-63312 nltk: NLTK: Arbitrary file read via StreamBackedCorpusView bypass
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anpicker, bparees, dschmidt, ebourniv, hasun, jfula, jlanda, jowilson, kshier, nyancey, ometelka, ptisnovs, sbunciak, simaishi, stcannon, syedriko, teagle, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in NLTK. This vulnerability, specifically within the `StreamBackedCorpusView` component, allows an attacker to bypass security enforcement by directly calling `builtins.open()` instead of the intended `pathsec.open()`. By controlling the `fileid` argument, an attacker can read arbitrary local files, including sensitive system files and application credentials, regardless of the `ENFORCE` setting.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-08-22 14:31:59 UTC 
NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.