CVE-2021-43396

FAUCET Score

CVE-2021-43396 is a data integrity vulnerability in the GNU C Library (glibc) 2.34, specifically within the iconvdata/iso-2022-jp-3.c component, affecting GNU and Oracle products. Remote attackers can inject a spurious null character via crafted ISO-2022-JP-3 data combined with an internal state reset, potentially corrupting data in certain iconv() applications. Rated with a CVSS score of 7.5 (High), this vulnerability has a network attack vector and low attack complexity, but the vendor notes it requires a separate application bug to be unintentionally triggered, limiting its direct security impact. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

Vendor	Product	Version(s)	CPE
		2.34CPE matchmatch criteria	cpe:2.3:a:gnu:glibc:2.34:::::::*
		22.1.3CPE matchmatch criteria	cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:22.1.3:::::::*
		22.1.0CPE matchmatch criteria	cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:22.1.0:::::::*
		22.1.2CPE matchmatch criteria	cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:22.1.2:::::::*
		22.2.0CPE matchmatch criteria	cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:22.2.0:::::::*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

NONE

Exploitability Score

3.9

Impact Score

3.6

CvssVersion

3.1

Exploit Intelligence

EPSS Score

3.06%

Probability of exploitation in next 30 days

EPSS Percentile

86.2%

Percentile rank of EPSS score among Peer Group

As of 2026-07-28

Model: v2026.06.15

This CVE's current EPSS score of 0.0306 is in the 75th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

microsoftpatch availablevia msrc

Product: 18810-16823Fixed in: 2.35-1

microsoftpatch availablevia msrc

Product: CBL Mariner 2.0 x64Fixed in: 2.35-1

microsoftpatch availablevia msrc

Product: CBL Mariner 2.0 ARMFixed in: 2.35-1

microsoftpatch availablevia msrc

Product: cbl2 glibc 2.35-1 on CBL Mariner 2.0Fixed in: 2.35-1

oraclepatch availablevia nvd_reference

View patch

Vendor Advisories (3)

microsoft2021-Dec/CVE-2021-43396

CVE-2021-43396

Dec 14, 2021

microsoft2021-Nov/CVE-2021-43396Important

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.

Nov 9, 2021

redhatCVE-2021-43396

glibc: conversion from ISO-2022-JP-3 with iconv may emit spurious NUL character on state reset

Nov 1, 2021

References

blog.tuxcare.com / vulnerability/vulnerability-in-iconv-identified-by-tuxcare-team-cve-2021-43396

ExploitThird Party Advisory

sourceware.org / bugzilla/show_bug.cgi

ExploitIssue TrackingThird Party Advisory

sourceware.org / git

oracle.com / security-alerts/cpujul2022.html

PatchThird Party Advisory