CVE-2025-4918VulnerabilityPublished 9 Jun 2025Updated 27 Jun 2026

Red Hat Security Advisory: firefox security update

Affects Red HatSource GCVE Database

Mentioned vulnerabilities

CVE-2025-4919

Not known to be exploited.

Data as of 25 Oct 2026, 19:02 UTC

Severity

High

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 9.5% chance of exploitation in 30 days – higher than 95% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

Red Hat has released updated Firefox packages (version 128.10.1-1.el8_2) for Red Hat Enterprise Linux 8.2 AUS to address these vulnerabilities. Users should apply these official updates promptly to remediate the issues. Detailed update instructions are available at https://access.redhat.com/articles/11258. No additional mitigations are specified or required beyond applying the vendor-provided update.

Description

Two security vulnerabilities affecting Mozilla Firefox and Thunderbird have been addressed by Red Hat in their Enterprise Linux 8.2 distribution. The issues involve out-of-bounds access errors during Promise object resolution and linear sum optimization, identified as CVE-2025-4918 and CVE-2025-4919 respectively. These vulnerabilities are rated as important by Red Hat Product Security. An update to Firefox version 128.10.1-1.el8_2 is available to remediate these issues.

Impact

The vulnerabilities involve out-of-bounds memory access, which can lead to memory corruption or crashes in Firefox and Thunderbird. Such issues may be exploitable to cause denial of service or potentially other impacts depending on the context of exploitation. Red Hat classifies the security impact as important, indicating a significant but not critical risk level.

Summary

Red Hat Product Security issued advisory RHSA-2025:8639 addressing two out-of-bounds access vulnerabilities in Firefox and Thunderbird (CVE-2025-4918 and CVE-2025-4919). These vulnerabilities relate to improper memory access when resolving Promise objects and optimizing linear sums, which could lead to potential security risks. The advisory applies to Red Hat Enterprise Linux Server AUS 8.2 x86_64 and provides updated Firefox packages (version 128.10.1-1.el8_2) to fix these issues. No CVSS scores are provided in the advisory, but the severity is rated as important by Red Hat.

CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 27 Jun 2026, 22:29 UTC

WeaknessesCWE-787

Technical details

References

Community reviews

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