Back Linuxsecurity

Fedora 43 Firefox Heap Overflow Security Advisory 2026

Linuxsecurity •LinuxSecurity Advisories • September 3, 2026

Keep your Linux systems secure and up to date with practical patching guidance. Review Linux Patching Best Practices ×

Mozilla Firefox is an open-source web browser, designed for standards

compliance, performance and portability.

NSS Release Notes Update NSS to 3.127.0 Bug 1869493 - Heap-buffer overflow in AES Keywrap. Bug 2052210 - Generate additional test message for Thunderbird (HTML with remote image). Bug 2052709 - Convert NSS 3.126 release notes to Markdown. Bug 2053831 - clang format. Bug 2054609 - remove cipher suite order exception from bug 946147. Bug 2054714 - avoid leaking stale ECH outer extensions across HRR. Bug 2054719 - fix content type tag for CMS AuthEnvelopedData plaintext. Bug 2056291 - remove support for pre-v1.0 PKCS#12. Bug 2056846 - Remove unused policy string callback to fix -Wunused-but-set- global. Bug 2057184 - Enable -Wunused-but-set-variable/-global in werror.py. Bug 2059176 - EC_DerivePublicKey() failure is not propagated in sftk_mkPrivKey(). Bug 2060118 - remove DH_GenParam support. Bug 2060720 - Round ECH ClientHelloInner padding up to a multiple of 32. Bug 2061107 - restore pkcs12.h for source compatibility. Bug 2063071 - make selfserv listen on IPv6 wild...

* Thu Aug 27 2026 Martin Stransky - 155.0-1 - Updated to 155.0 * Wed Aug 26 2026 Martin Stransky - 154.0-6 - Use new (layer) compositor mode for HDR

Fedora Update Notification FEDORA-2026-208add2041 2026-09-03 00:57:56.095868+00:00 Name : firefox Product : Fedora 43 Version : 155.0 Release : 1.fc43 URL : Summary : Mozilla Firefox Web browser Description : Mozilla Firefox is an open-source web browser, designed for standards compliance, performance and portability.

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-208add2041' at the command line. For more information, refer to the dnf documentation available at

Get the latest News and Insights

Get the latest Linux and open source security news straight to your inbox.

Linux Security - Your source for Top Linux News, Advisories, HOWTOs and Feature Releases

The full story

This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Critical Heap Buffer Overflow Vulnerabilities in Fedora NSS and Firefox Recent updates for Fedora 43 and 44 address critical heap buffer overflow vulnerabilities in Network Security Services (NSS) and Mozilla Firefox. The vulnerabilities, identified as Bug 1869493, affect versions 3.127.0 of NSS and Firefox 155.0. Exploitation could lead to unauthorized access or manipulation of sensitive data. Users are urged to update their systems immediately to mitigate risks. The vulnerabilities are associated with improper handling of memory, which could allow attackers to execute arbitrary code. The patches are available through the 'dnf' update program. No active exploitation has been confirmed in the wild as of the latest reports. The updates were released on September 3, 2026. 4 sources 61

Extracted Entities

Fedora 43 Firefox Heap Overflow Security Advisory 2026

The full story

Extracted Entities

Companies (1)

CWE Weaknesses (1)

Platforms (4)