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HIGH

CVE-2025-5269

CVSS v3

8.1

HIGH

EPSS Score

0.5 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • firefoxAlmaLinux:10all versions · fixed in 128.11.0-1.el10_0
  • firefoxAlmaLinux:9all versions · fixed in 128.11.0-1.el9_6.alma.1and 2 other packages
  • firefoxAlmaLinux:8all versions · fixed in 128.11.0-1.el8_10.alma.1and 1 other package
  • thunderbirdAlmaLinux:10all versions · fixed in 128.11.0-1.el10_0.alma.1

Vendor advisories

  • CVE-2025-5269 Red Hat Product Security249 products fixed · 8 known affected

    firefox: thunderbird: Memory safety bug

    rhel10/firefox-flatpak.src as a component of Red Hat Enterprise Linux 10 · rhel10/thunderbird-flatpak.src as a component of Red Hat Enterprise Linux 10 · firefox as a component of Red Hat Enterprise Linux 6

  • RHSA-2025:9155 Red Hat Product Security21 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:9072 Red Hat Product Security17 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:9071 Red Hat Product Security17 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:9077 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:9074 Red Hat Product Security5 products fixed

    Red Hat Security Advisory: firefox security update

16 more advisories

Full record on NVD

Description

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2025-05-27
Last Modified
2026-04-13

Frequently asked questions

What is CVE-2025-5269?

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

Is CVE-2025-5269 actively exploited?

Active exploitation of CVE-2025-5269 has not been confirmed. Its EPSS score was 0.5% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-5269?

CVE-2025-5269 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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