CVE-2021-43396
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force...
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
CVE-2021-43396- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:P/A:N - Updated
- 2026-11-02
CVE List No score
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
CVE-2021-43396- Updated
- 2026-11-02
EUVDEUVD-2021-30331 No score
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
EUVD-2021-30331- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-73g2-m4v3-6c2h
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force...
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases.
- Record
GHSA-73g2-m4v3-6c2h- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVAZL-6443
CVE-2021-43396 affecting package glibc for versions less than 2.35-1
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
AZL-6443- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSV
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
CVE-2021-43396- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
Show 5 moreShow less
OSVDEBIAN-CVE-2021-43396
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases. NOTE: the vendor states "the bug cannot be invoked through user input and requires iconv to be invoked with a NULL inbuf, which ought to require a separate application bug to do so unintentionally. Hence there's no security impact to the bug.
- Record
DEBIAN-CVE-2021-43396- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVOESA-2021-1438
glibc security update
The GNU C Library project provides the core libraries for the GNU system and GNU/Linux systems, as well as many other systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more.
Security Fix(es):
In iconvdata/iso-2022-jp-3.c in the GNU C Library (aka glibc) 2.34, remote attackers can force iconv() to emit a spurious '\0' character via crafted ISO-2022-JP-3 data that is accompanied by an internal state reset. This may affect data integrity in certain iconv() use cases.(CVE-2021-43396)
- Record
OESA-2021-1438- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVCLSA-2021-1636389414 No score
Fix CVE(s): CVE-2021-3326, CVE-2021-43396
- SECURITY UPDATE: assertion failure in ISO-2022-JP-3 module
- debian/patches/any/CVE-2021-3326.patch: enqueue a second wide character which cannot be written immediately in the state variable.
- CVE-2021-3326
- SECURITY UPDATE: emission of a spurious '\0' character on state reset
- debian/patches/any/CVE-2021-3326.patch: check actual stored character in state reset code.
- CVE-2021-43396
- Record
CLSA-2021-1636389414- Updated
- 2026-11-02
OSVCLSA-2021-1636389447 No score
Fixed CVEs in glibc: CVE-2021-43396, CVE-2021-3326
- CVE-2021-3326: avoid denial of service due to a failed assertion
- CVE-2021-43396: check actual stored character in state reset code
- Record
CLSA-2021-1636389447- Updated
- 2026-11-02
OSVCLSA-2021-1637583639 No score
Fix of CVE: CVE-2021-3326, CVE-2021-43396
- CVE-2021-3326: avoid denial of service due to a failed assertion
- CVE-2021-43396: check actual stored character in state reset code
- Record
CLSA-2021-1637583639- Updated
- 2026-11-02
Affected products
- gnu glibc
- oracle communications cloud native core binding support function
- oracle communications cloud native core network function cloud native environment
- oracle communications cloud native core network repository function
- oracle communications cloud native core security edge protection proxy
- oracle communications cloud native core unified data repository
- oracle enterprise operations monitor
- siemens simatic s7-1500 cpu 1518-4 pn/dp mfp
- siemens simatic s7-1500 cpu 1518f-4 pn/dp mfp
- siemens siplus s7-1500 cpu 1518-4 pn/dp mfp
Affected packages
| Package | Affected | Fixed |
|---|---|---|
glibcAzure Linux:2 |
before 2.35-1 | 2.35-1 |
glibc-docTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
glibc-sourceTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc-binTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc-dev-binTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6TuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6-devTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6-dev-i386TuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6-dev-x32TuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6-i386TuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
Show 25 moreShow less
| Package | Affected | Fixed |
|---|---|---|
libc6-picTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
libc6-x32TuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
localesTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
locales-allTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
multiarch-supportTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
nscdTuxCare:Ubuntu:16.04 |
before 2.23-0ubuntu11.5 | 2.23-0ubuntu11.5 |
glibcTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-commonTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-develTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-headersTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-staticTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-utilsTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
nscdTuxCare:OracleLinux:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibcTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-commonTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-develTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-headersTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-staticTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibc-utilsTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
nscdTuxCare:CentOS:6 |
before 2.12-2.215.el6.cloudlinux.els | 2.12-2.215.el6.cloudlinux.els |
glibcDebian:12 |
before 2.32-5 | 2.32-5 |
glibcDebian:13 |
before 2.32-5 | 2.32-5 |
glibcDebian:14 |
before 2.32-5 | 2.32-5 |
glibcopenEuler:20.03-LTS-SP1 |
before 2.28-79.oe1 | 2.28-79.oe1 |
glibcopenEuler:20.03-LTS-SP2 |
before 2.28-79.oe1 | 2.28-79.oe1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-43396 is a high vulnerability (CVSS 7.5) in Gnu Glibc, published November 4, 2021. Its validity is disputed. EPSS puts the chance of exploitation in the next 30 days at 3.29%, the 88th percentile. Fixed in glibc 2.35-1.
References
sourceware.org/bugzilla/show_bug.cgi?id=28524
blog.tuxcare.com/vulnerability/vulnerability-in-iconv-identified-by-tuxcare-team-cve-2021-43396
oracle.com/security-alerts/cpujul2022.html
cert-portal.siemens.com/productcert/html/ssa-398330.html
nvd.nist.gov/vuln/detail/CVE-2021-43396
Show 7 moreShow less
github.com/advisories/GHSA-73g2-m4v3-6c2h
errata.cloudlinux.com/ubuntu16_04/CLSA-2021-1636389414
security-tracker.debian.org/tracker/CVE-2021-43396
openeuler.org/en/security/safety-bulletin/detail.html?id=openEuler-SA-2021-1438