PT-2026-41910 · Mozilla+1 · Thunderbird+2

Yaqoub Aldurayhim · CVE-2026-8956 · Published 2026-05-19 · Updated 2026-06-29

Positive Technologies (AI Summary)

CVSS v3.1

9.8

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 151 Firefox ESR versions prior to 140.11 Thunderbird versions prior to 151 Thunderbird versions prior to 140.11

Description An integer overflow exists in the Networking: JAR component. An integer overflow occurs when an arithmetic operation attempts to create a numeric value that is too large to be represented within the available storage area.

Recommendations Update Firefox to version 151. Update Firefox ESR to version 140.11. Update Thunderbird to version 151. Update Thunderbird to version 140.11.

Fix

DoS

Integer Overflow

Weakness Enumeration

CWE-190

Related Identifiers

ALSA-2026:21378

ALSA-2026:21380

ALSA-2026:21381

ALSA-2026:21382

ALSA-2026:22325

ALSA-2026:22643

CVE-2026-8956

OESA-2026-2392

OESA-2026-2393

OESA-2026-2394

OESA-2026-2465

OPENSUSE-SU-2026:10813-1

OPENSUSE-SU-2026:10863-1

OPENSUSE-SU-2026:10864-1

OPENSUSE-SU-2026:21168-1

Affected Products

Firefox

Rocky Linux

Thunderbird

References · 195

• https://errata.rockylinux.org/RLSA-2026:21378 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-48/#CVE-2026-8956 · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2026-22643.html · Vendor Advisory
• https://mozilla.org/en-US/security/advisories/mfsa2026-50 · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-21378.html · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:21380 · Vendor Advisory
• https://errata.almalinux.org/8/ALSA-2026-21382.html · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2026-21382.html · Vendor Advisory
• https://errata.almalinux.org/10/ALSA-2026-22325.html · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:21382 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-8956 · Security Note
• https://mozilla.org/en-US/security/advisories/mfsa2026-48 · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-21381.html · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-8957 · Security Note
• https://osv.dev/vulnerability/ALSA-2026:21381 · Vendor Advisory