CVE-2026-97399: One-byte overread in strncasecmp on Power8

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.3%

EPSS score, percentile 20.6 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

3.7 Low

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• from 2.24 to before 2.45

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Advisories and patches

• sourceware.org (Vendor advisory)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Versions not listed are: unaffected.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

The strncasecmp function in the GNU C Library 2.24 and later optimized for the Power8 architecture may read one byte beyond the input size limit, which may crash a program when that byte is not readable. This condition may happen when the input strings to the strncasecmp function are attacker controlled in an application and they match all the way up to the edge of their page and the neighbourin…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-97399 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 28 Sep 2026.
• The CVE record carries a CVSS v3.1 base score of 3.7 (Low), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.3% (percentile 20.6), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
• The credits in the CVE record name AISLE as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

One-byte overread in strncasecmp on Power8

The strncasecmp function in the GNU C Library 2.24 and later optimized for the Power8 architecture may read one byte beyond the input size limit, which may crash a program when that byte is not readable. This condition may happen when the input strings to the strncasecmp function are attacker controlled in an application and they match all the way up to the edge of their page and the neighbouring page is either not mapped or is not readable.

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline