CVE-2021-3420

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-05 · updated 2026-06-17
Weakness: CWE-190

Description

A flaw was found in newlib in versions prior to 4.0.0. Improper overflow validation in the memory allocation functions mEMALIGn, pvALLOc, nano_memalign, nano_valloc, nano_pvalloc could case an integer overflow, leading to an allocation of a small buffer and then to a heap-based buffer overflow.

Affected products

Fedoraproject Fedora: 32, 33, 34
Red Hat newlib: before 4.0.0 — fixed in 4.0.0

How to fix

Upgrade to a fixed version: Red Hat newlib 4.0.0. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1934088
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AEBF6YHWFNCBW5A2ENSQ3Z56ELF4MTRE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AMK54N6UOPBFFX2YT32TWSAEFTHGSKAA/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQZEUANAWBBAOC4TF5PTPJVLMUR7SFD/
https://bugzilla.redhat.com/show_bug.cgi?id=1934088
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AEBF6YHWFNCBW5A2ENSQ3Z56ELF4MTRE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AMK54N6UOPBFFX2YT32TWSAEFTHGSKAA/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQZEUANAWBBAOC4TF5PTPJVLMUR7SFD/

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