CVE-2026-122054

BIG-HKSCS decoding hang on crafted input

5.9 MediumFix available

Converting crafted BIG-HKSCS input to UCS-4 or the internal wide character encoding, for example with iconv, in the GNU C Library version 2.18 through 2.31 may result in the converter making no progress, causing the calling application to hang.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.45%Unchanged since Nov 5, 2026

What each source reports

CVE List Score used 5.9

BIG-HKSCS decoding hang on crafted input

Record: CVE-2026-122054
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-835
Updated: 2026-11-04

EUVDEUVD-2026-117002 5.9

Record: EUVD-2026-117002
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-04

GitHub AdvisoriesGHSA-5wwm-g25c-cpx8 5.9

Converting crafted BIG-HKSCS input to UCS-4 or the internal wide character encoding, for example...

Record: GHSA-5wwm-g25c-cpx8
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-835
Updated: 2026-11-04

NVD 5.9

Record: CVE-2026-122054
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-835
Updated: 2026-11-04

OSV 5.9

BIG-HKSCS decoding hang on crafted input

Record: CVE-2026-122054
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-835
Updated: 2026-11-05

OSVDEBIAN-CVE-2026-122054 5.9

Record: DEBIAN-CVE-2026-122054
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-05

OSVUBUNTU-CVE-2026-122054 5.9

Record: UBUNTU-CVE-2026-122054
CVSS 3.1: 5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-06

Affected products

the gnu c library glibc

Affected packages

Affected packages
Package	Affected	Fixed
`glibc` Debian:12	before 2.32-1	2.32-1
`glibc` Debian:13	before 2.32-1	2.32-1
`glibc` Debian:14	before 2.32-1	2.32-1
`glibc` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 2.21-0ubuntu42.21-0ubuntu52.21-0ubuntu62.23-0ubuntu12.23-0ubuntu2 Show 18 moreShow less 2.23-0ubuntu32.23-0ubuntu42.23-0ubuntu52.23-0ubuntu62.23-0ubuntu72.23-0ubuntu92.23-0ubuntu102.23-0ubuntu112.23-0ubuntu11.22.23-0ubuntu11.32.23-0ubuntu11.3+esm12.23-0ubuntu11.3+esm22.23-0ubuntu11.3+esm32.23-0ubuntu11.3+esm52.23-0ubuntu11.3+esm62.23-0ubuntu11.3+esm72.23-0ubuntu11.3+esm82.23-0ubuntu11.3+esm9	None known
`glibc` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 2.26-0ubuntu22.26-0ubuntu2.12.27-0ubuntu22.27-0ubuntu32.27-3ubuntu1 Show 11 moreShow less 2.27-3ubuntu1.22.27-3ubuntu1.32.27-3ubuntu1.42.27-3ubuntu1.52.27-3ubuntu1.62.27-3ubuntu1.6+esm12.27-3ubuntu1.6+esm22.27-3ubuntu1.6+esm32.27-3ubuntu1.6+esm42.27-3ubuntu1.6+esm52.27-3ubuntu1.6+esm6	None known
`glibc` Ubuntu:Pro:20.04:LTS	All versions, plus listed versions 2.30-0ubuntu22.30-0ubuntu32.31-0ubuntu52.31-0ubuntu62.31-0ubuntu7 Show 13 moreShow less 2.31-0ubuntu92.31-0ubuntu9.12.31-0ubuntu9.22.31-0ubuntu9.32.31-0ubuntu9.72.31-0ubuntu9.92.31-0ubuntu9.122.31-0ubuntu9.142.31-0ubuntu9.152.31-0ubuntu9.162.31-0ubuntu9.172.31-0ubuntu9.182.31-0ubuntu9.18+esm1	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, references	OSV
Nov 5, 2026	affected, aliases, published, references	OSV
Nov 5, 2026	affected, aliases, facts, references	OSV
Nov 4, 2026	published, references	CVE List, EUVD, GitHub Advisories, NVD
Nov 4, 2026	published	EUVD, NVD
Nov 4, 2026	references, severity, title	CVE List
Nov 4, 2026	aliases, cwes, references, severity, title	GitHub Advisories
Nov 4, 2026	first indexed	EUVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-122054 is a medium vulnerability (CVSS 5.9) in The Gnu C Library Glibc, published November 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.45%, the 38th percentile. Fixed in glibc 2.32-1.