Buffer overflow in The GNU C Library Glibc
CVE-2026-18374
Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled. This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for `ccs` should not pass them through without validation.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.001 (3.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 3.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.001 · change: -0.000
Affected products
Weakness classification (CWE)
References
- 3ff69d7a-14f2-4f67-a097-88dee7810d18 (issue-tracking)
- 3ff69d7a-14f2-4f67-a097-88dee7810d18 (vendor-advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2026-18374?
- CVE-2026-18374 is a medium-severity vulnerability in The GNU C Library Glibc, classified under Out-of-bounds Write. CVSS score: 4.9/10. Published 2026-08-27.
- How severe is CVE-2026-18374?
- Medium severity. CVSS v3 base score is 4.9 out of 10.