CVE-2026-4437
It was discovered that the GNU C Library iconv function incorrectly handled certain IBM character sets. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-4046) It was discovered that the GNU C Library DNS functions incorrectly handled certain DNS server responses when using gethostbyaddr or gethostbyaddr_r. An attacker in a privileged network position could possibly use this issue to cause an application to violate DNS specification or obtain incorrect hostname information. This issue only affected Ubuntu 24.04 LTS. (CVE-2026-4437, CVE-2026-4438) It was discovered that the GNU C Library deprecated debugging functions incorrectly enforced caller-supplied buffer lengths. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-5435) It was discovered that the GNU C Library scanf family of functions contained a heap buffer overflow when processing certain format specifiers. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-5450) It was discovered that the GNU C Library ungetwc function incorrectly handled certain character encodings. An attacker could possibly use this issue to obtain sensitive information or cause a denial of service. (CVE-2026-5928) It was discovered that the GNU C Library deprecated debugging functions incorrectly validated DNS response record data. An attacker could possibly use this issue to cause a denial of service or obtain sensitive information. (CVE-2026-6238)
CSIRTS triage
- What
- Multiple vulnerabilities in the GNU C Library could lead to denial of service, arbitrary code execution, or information disclosure.
- Who is affected
- Users of the GNU C Library on Ubuntu 24.04 LTS.
- Urgency
- Remediation is urgent due to the critical nature of the vulnerabilities and potential for exploitation.
- Action
- Update the GNU C Library to the latest patched version.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 25% of all EPSS-scored CVEs.
Advisory coverage (2)
- medium[UPDATE] [medium] GNU libc: Multiple vulnerabilities allow manipulation of DNS responsescert-bund · 2026-07-28
- unknownUSN-8611-1: GNU C Library vulnerabilitiesubuntu · 2026-07-27
External references
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