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Public proof of conceptFix available

CVE-2025-1009

A public proof of concept exists; no exploitation attested.

  • Published2025-02-04
  • Fixed in135.0 · 128.7.0 · 115.20.0
  • WeaknessCWE-416

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 could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

Timeline

dates in UTC
  1. 2025-02-0414:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-1009?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-1009?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Mozilla firefox
BranchAffectedFixed in
135.0< 135.0135.0
128.x≥ 128.1.0, < 128.7.0128.7.0
115.20< 115.20.0115.20.0
Mozilla thunderbird
BranchAffectedFixed in
135.0≥ 131.0, < 135.0135.0
128.x≥ 128.0.1, < 128.7.0128.7.0

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

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

  • firefoxAlmaLinux:9all versions · fixed in 128.7.0-1.el9_5and 1 other package
  • firefoxAlmaLinux:8all versions · fixed in 128.7.0-1.el8_10
  • thunderbirdAlmaLinux:9all versions · fixed in 128.7.0-1.el9_5.alma.1
  • thunderbirdAlmaLinux:8all versions · fixed in 128.7.0-1.el8_10.alma.1

Full record on NVD

Fix

  1. Update Mozilla firefox to 135.0 · 128.7.0 · 115.20.0

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2025-03-14
  • OpenCVESSVC decisionpoc—
  • CISA-ADPCVSS 3.19.82025-02-05
  • NVDCVSS 3.19.8read 2026-10-23
  • CISA-ADPweakness (CWE)CWE-4162025-02-05
  • NVDweakness (CWE)CWE-416read 2026-10-23
  • FIRST EPSSEPSS score1.2 %2026-10-23
  • OSVaffected packages—

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
2025-02-04
Last Modified
2026-10-05
NVD status
Modified

Frequently asked questions

What is CVE-2025-1009?

An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

Is CVE-2025-1009 actively exploited?

A proof-of-concept exploit exists for CVE-2025-1009, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2025-1009?

CVE-2025-1009 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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