# CVE-2021-43396: Other in n/a

> A bug in glibc's iconv function can emit spurious null characters during ISO-2022-JP-3 conversion, potentially affecting data integrity, though vendor claims no security impact.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Nov 2021
- **Updated:** 14 Oct 2026
- **Also known as:** AZL-6443, DEBIAN-CVE-2021-43396, GHSA-73g2-m4v3-6c2h, MINI-236x-9gmr-w9mj, OESA-2021-1438

## What is CVE-2021-43396?

CVE-2021-43396 is a high-severity vulnerability in Gnu Glibc, published on 4 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

## Which versions are affected by CVE-2021-43396?

It affects 7 products.


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.

## How do I fix CVE-2021-43396?

No fix published yet.

## Is CVE-2021-43396 being exploited?

There is no known exploitation of CVE-2021-43396 in the wild and no public exploit code.

## Other vulnerabilities in Gnu Glibc

- [CVE-2026-5450](https://insights.sbomify.com/CVE-2026-5450/): scanf %mc off-by-one heap buffer overflow (critical 9.8)
- [CVE-2023-25139](https://insights.sbomify.com/CVE-2023-25139/): Memory corruption in n/a (critical 9.8)
- [CVE-1999-0199](https://insights.sbomify.com/CVE-1999-0199/): Other in n/a (critical 9.8)
- [CVE-2019-1010022](https://insights.sbomify.com/CVE-2019-1010022/): Security feature bypass in glibc (critical 9.8)
- [CVE-2005-3590](https://insights.sbomify.com/CVE-2005-3590/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43396 and fix it if it is affected.

What it is: CVE-2021-43396 is a high-severity vulnerability in Gnu Glibc, published on 4 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43396 in the wild and no public exploit code.

Affected product: Gnu Glibc. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-43396/ (Markdown: https://insights.sbomify.com/CVE-2021-43396/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43396
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43396
- OSV: https://osv.dev/vulnerability/CVE-2021-43396

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43396/
Summaries are generated and may contain mistakes; the official description above is the record.