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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…
Medium4.9EPSS 0.14%
- Published
- Updated
- Reserved
- Assigned by
- glibc
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| glibcCNA (assigner) | 3.1 | Medium4.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L |
| NVDNVD · Awaiting Analysis | 3.1 | Medium4.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L |
- EPSS (exploitation in 30 days)
- 0.14% · top 96% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.9.
Weakness
- Buffer overflow in fopen mode argument processing
- CWE-787 Out-of-bounds write (opens in a new tab)All about CWE-787 and its CVEs
Affected products
- affected < 2.45
References (3)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-18374)Record last updated .