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No exploitation reportedFix available

CVE-2025-4918

Out-of-bounds access when resolving Promise objects

No exploitation reported by the sources we read.

  • Published2025-05-17
  • Fixed in138.0.4 · 128.10.1 · 115.23.1
  • WeaknessCWE-125 · CWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.

Timeline

dates in UTC
  1. 2025-05-1722:15CVE publishedNVD

Versions per branch

NVD
Mozilla firefox
BranchAffectedFixed in
138.0< 138.0.4138.0.4
128.10≥ 116.0, < 128.10.1128.10.1
115.23< 115.23.1115.23.1
Mozilla thunderbird
BranchAffectedFixed in
138.0≥ 138.0, < 138.0.2138.0.2
128.10< 128.10.2128.10.2

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA2 products

As mozilla, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Mozilla Firefox

    Not affected ≥ 115.23.1, ≤ 115.* · ≥ 128.10.1, ≤ 128.* · ≥ 138.0.4

  • Mozilla Thunderbird

    Not affected ≥ 128.10.2, ≤ 128.* · ≥ 138.0.2

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-04-13

Distribution builds and vendor advisories

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

  • firefoxWolfiall versions · fixed in 128.10.1-r0
  • firefoxRocky Linux:10all versions · fixed in 0:128.10.1-1.el10_0
  • firefoxRocky Linux:8all versions · fixed in 0:128.10.1-1.el8_10
  • firefoxRed Hat:rhel_tus:8.8::appstreamall versions · fixed in 0:128.10.1-1.el8_8and 2 other packages
  • firefoxRed Hat:rhel_tus:8.6::appstreamall versions · fixed in 0:128.10.1-1.el8_6and 2 other packages
  • firefoxRed Hat:rhel_eus:9.4::appstreamall versions · fixed in 0:128.10.1-1.el9_4and 3 other packages
  • firefoxRed Hat:rhel_eus:9.2::appstreamall versions · fixed in 0:128.10.1-1.el9_2and 3 other packages
  • firefoxRed Hat:rhel_els:7all versions · fixed in 0:128.10.1-1.el7_9and 1 other package

80 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-4918 Red Hat Product Security253 products fixed · 8 known affected

    firefox: thunderbird: Out-of-bounds access when resolving Promise objects

    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 · +5 more

  • RHSA-2025:8807 Red Hat Product Security11 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:8756 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2025:8645 Red Hat Product Security21 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2025:8642 Red Hat Product Security13 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2025:8631 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: thunderbird security update

16 more advisories

Full record on NVD

Fix

  1. Update Mozilla firefox to 138.0.4 · 128.10.1 · 115.23.1
  2. Vendor fix Red Hat Product Security RHSA-2025:8807 · 11 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  3. Workaround from the vendor Red Hat Product Security RHSA-2025:8807 · 11 productsNo mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2025-05-17
Last Modified
2026-09-30
NVD status
Modified
GitHub Advisory
GHSA-fhgm-mxgh-gfpj

Frequently asked questions

What is CVE-2025-4918?

An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.

Is CVE-2025-4918 actively exploited?

Active exploitation of CVE-2025-4918 has not been confirmed. Its EPSS score was 9.5% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-4918?

CVE-2025-4918 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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