How severe is CVE-2026-89087?

CVE-2026-89087 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-89087 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-89087?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-89087 published?

CVE-2026-89087 was published on 2026-09-10 and last updated on 2026-09-14.

CVE-2026-89087

CVE-2026-89087 is a high-severity vulnerability with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-573.

Key facts

Severity: High (CVSS 3.x base score 7.3)
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-573
Published: 2026-09-10
Last modified: 2026-09-14

Description

The cstruct package before 6.3.0 for OCaml mishandles indexes.

Frequently asked questions

What is CVE-2026-89087?: The cstruct package before 6.3.0 for OCaml mishandles indexes.
How severe is CVE-2026-89087?: CVE-2026-89087 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-89087 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-89087?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-89087 published?: CVE-2026-89087 was published on 2026-09-10 and last updated on 2026-09-14.

References

https://osv.dev/vulnerability/OSEC-2026-20

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