SB2026100236 - Fedora 43 update for glibc
Published: October 2, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 5 vulnerabilities.
1) Heap-based buffer overflow (CVE-ID: CVE-2026-5450)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow. A remote attacker can pass specially crafted data to the application, trigger a heap-based buffer overflow and execute arbitrary code on the target system.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
2) Buffer Over-read (CVE-ID: CVE-2026-6238)
CWE-ID: CWE-126 - Buffer over-read
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to crash the target application or read uninitialized data.
The vulnerability exists due to deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2.43 fail to validate the RDATA content against the RDATA length in a DNS response when processing A6, CERT, LOC, TKEY or TSIG records. A remote attacker can craft a DNS response, causing a target application to crash or read uninitialized memory.
3) Out-of-bounds write (CVE-ID: CVE-2026-5435)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 5.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library fail to enforce the caller-supplied buffer length, and can result in an out-of-bounds write when printing TSIG records.. A remote attacker can create a specially crafted file, trick the victim into opening it using the affected software, trigger an out-of-bounds write and execute arbitrary code on the target system.
4) Buffer under-read (CVE-ID: CVE-2026-5928)
CWE-ID: CWE-127 - Buffer Under-read
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to perform a denial of service attack.
The vulnerability exists due to calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has overlaps between its single byte and multi-byte character encodings, in the GNU C Library may result in an attempt to read bytes before an allocated buffer. A remote attacker can pass specially crafted data to the application, causing disclosure of neighboring data in the heap, or a program crash.
5) Reachable assertion (CVE-ID: CVE-2026-4046)
CWE-ID: CWE-617 - Reachable Assertion
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a reachable assertion in the iconv function when processing specially crafted input using the IBM1390 or IBM1399 character sets. A remote attacker can supply malicious input remotely to cause a denial of service.
Remediation
Install update from vendor's website.