CVE-2026-81725Medium· 5.9▾ SunlitA flaw was found in NLTK, specifically within the Pl196xCorpusReader component. A remote attacker can exploit this by supplying malformed Text Encoding Initiative (TEI) blocks containing numerous unmatched opening tags. This triggers a reg…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 32.5 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Sep 2.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CSAF
0.2%
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— → 5.9
0.2% → 0.4%
Last analysed / modified upstream
A flaw was found in NLTK, specifically within the Pl196xCorpusReader component. A remote attacker can exploit this by supplying malformed Text Encoding Initiative (TEI) blocks containing numerous unmatched opening tags. This triggers a regular expression denial of service (ReDoS) vulnerability, causing quadratic CPU consumption and leading to a denial of service.
nltk: NLTK: Regular Expression Denial of Service via malformed TEI blocks — rated Moderate by Red Hat. Released 2026-08-27, updated 2026-10-19.
Affected:
Fixed:
No fix planned:
Not affected:
For Red Hat OpenShift AI 3.4.5 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update:
https://docs.redhat.com/en/documentation/red_hat_openshift_ai/ https://access.redhat.com/errata/RHSA-2026:84734
Workarounds / mitigations:
Affected packages:
nltk < 3.10.3Patched in:
nltk 3.10.3Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-80205High· 7.5nltk: NLTK: Denial of Service via unvalidated regular expressions (CVE-2026-80205)
CVE-2026-79674High· 7.5nltk: NLTK: Information disclosure via path traversal in corpus-reader constructors (CVE-2026-79674)
CVE-2026-79675High· 8.1nltk: NLTK before 3.10.3 JVM Argument Injection via Per-Call Options (CVE-2026-79675)
CVE-2026-81722High· 7.5nltk: nltk PorterStemmer: Denial of Service due to inefficient token processing (CVE-2026-81722)
CVE-2026-59884Medium· 5.9python-pyasn1: pyasn1: Denial of Service via crafted BER input (CVE-2026-59884)
CVE-2026-59885High· 7.5pyasn1: python-pyasn1: pyasn1: Denial of Service via crafted ASN.1 OBJECT IDENTIFIER (CVE-2026-59885)