Eglibc: Passing an effectively empty string to the ,ccs= syntax extension of the mode argument in the fopen function
Affects eglibcSource GCVE Database
Not known to be exploited · CVSS 4.9 Medium.
Data as of 9 Nov 2026, 14:21 UTC
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 27 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu Pro 20.04 LTSglibcpkg:deb/ubuntu/glibc?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSglibcpkg:deb/ubuntu/glibc?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in– |
Ubuntu Pro 16.04 LTSglibcpkg:deb/ubuntu/glibc?arch=source&distro=esm-infra/xenialOther threats | Affected
| Fixed in– |
Ubuntu Pro 14.04 LTSeglibcpkg:deb/ubuntu/eglibc?arch=source&distro=esm-infra-legacy/trustyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users and administrators should validate and sanitize any user-supplied values passed to the ,ccs= syntax extension in fopen mode strings to prevent exploitation. Avoid passing effectively empty strings to this syntax extension.
Description
A heap buffer overflow vulnerability exists in the GNU C Library (eglibc) version 2.45 or earlier when an effectively empty string is passed to the ,ccs= syntax extension of the mode argument in the fopen function. This flaw arises if the mode string input is attacker-controlled. This usage pattern is uncommon in typical GNU/Linux applications, and user-supplied ccs values should be validated before use.