How severe is CVE-2026-86139?

CVE-2026-86139 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2026-86139 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-86139?

CVE-2026-86139 affects Xmlsoft Libxml2. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-86139?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-86139 published?

CVE-2026-86139 was published on 2026-09-05 and last updated on 2026-09-15.

CVE-2026-86139

CVE-2026-86139 is a medium-severity vulnerability in Xmlsoft Libxml2 with a CVSS 3.x base score of 6.9. 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-190.

Key facts

Severity: Medium (CVSS 3.x base score 6.9)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Xmlsoft Libxml2
Published: 2026-09-05
Last modified: 2026-09-15

Description

In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

Frequently asked questions

What is CVE-2026-86139?: In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.
How severe is CVE-2026-86139?: CVE-2026-86139 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-86139 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-86139?: CVE-2026-86139 affects Xmlsoft Libxml2. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-86139?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-86139 published?: CVE-2026-86139 was published on 2026-09-05 and last updated on 2026-09-15.

References

Affected products (1)

cpe:2.3:a:xmlsoft:libxml2:*:*:*:*:*:*:*:*

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