ESB-2026.4074 PUBLISHED CVSS 8.800000190734863 HIGH

=========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2026.4074 thunderbird security update 23 April 2026 =========================================================================== AUSCERT Security Bulletin Summary --------------------------------- Product: thunderbird Publisher: Red Hat Operating System: Red Hat Resolution: Patch/Upgrade CVE Names: CVE-2026-33416 CVE-2026-33636 CVE-2026-5732 CVE-2026-5731 CVE-2026-5734 Original Bulletin: https://access.redhat.com/errata/RHSA-2026:9638 Comment: CVSS (Max): 8.8 CVE-2026-5734 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) CVSS Source: Red Hat Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H EPSS (Max): 0.1% (20th) CVE-2026-5731 2026-04-21 - --------------------------BEGIN INCLUDED TEXT-------------------- RHSA-2026:9638 - Security Advisory Issued: 2026-04-22 Updated: 2026-04-22 Synopsis Thunderbird security update Type/Severity Security Advisory: Important Topic An update for thunderbird is now available for Red Hat Enterprise Linux 10. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section. Description Mozilla Thunderbird is a standalone mail and newsgroup client. Security Fix(es): o libpng: libpng: Arbitrary code execution due to use-after-free vulnerability (CVE-2026-33416) o libpng: libpng: Information disclosure and denial of service via out-of-bounds read/write in Neon palette expansion (CVE-2026-33636) o thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 (CVE-2026-5734) o thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 (CVE-2026-5731) o firefox: thunderbird: Incorrect boundary conditions, integer overflow in the Graphics: Text component (CVE-2026-5732) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section. Solution For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Affected Products o Red Hat Enterprise Linux for x86_64 10 x86_64 o Red Hat Enterprise Linux for IBM z Systems 10 s390x o Red Hat Enterprise Linux for Power, little endian 10 ppc64le o Red Hat Enterprise Linux for ARM 64 10 aarch64 Fixes o BZ - 2451805 - CVE-2026-33416 libpng: libpng: Arbitrary code execution due to use-after-free vulnerability o BZ - 2451819 - CVE-2026-33636 libpng: libpng: Information disclosure and denial of service via out-of-bounds read/write in Neon palette expansion o BZ - 2455897 - CVE-2026-5734 thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 o BZ - 2455901 - CVE-2026-5731 thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2 o BZ - 2455908 - CVE-2026-5732 firefox: thunderbird: Incorrect boundary conditions, integer overflow in the Graphics: Text component CVEs o CVE-2026-5731 o CVE-2026-5732 o CVE-2026-5734 o CVE-2026-33416 o CVE-2026-33636 References o https://access.redhat.com/security/updates/classification/#important - --------------------------END INCLUDED TEXT---------------------- You have received this e-mail bulletin as a result of your organisation's registration with AUSCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AUSCERT's members. As AUSCERT did not write the document quoted above, AUSCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AUSCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://portal.auscert.org.au/bulletins/ =========================================================================== AUSCERT The University of Queensland, Brisbane QLD 4072 Australia e: auscert@auscert.org.au t: +61 (0)7 3365 4417 Allies in Cyber Security ===========================================================================

Risk Scores

CVSS v3.1
8.800000190734863
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Products

VendorProductVersions
Red Hatthunderbird

Timeline

References

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