CVE Intelligence
Medium

CVE-2023-4045 — Offscreen Canvas did not properly track cross-origin tainting, which could have been used to...

Offscreen Canvas did not properly track cross-origin tainting, which could have been used to access image data from another site in violation of same-origin policy. This vulnerability affects Firefox < 116, Firefox ESR < 102.14, and Firefox ESR < 115.1.

Published Aug 1, 2023 · Updated Oct 24, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: mozilla

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.6% (30-day exploitation probability)+7
  • Technical severity (medium)+3
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.59%
ahead of 48% of scored CVEs · Oct 28, 2026
Affects
Debian
Debian Linux and 2 more
CVSS base
5.3
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Mozilla Firefox, Mozilla Firefox ESR).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Debian Debian Linux version 11.0version 12.0 Vulnerable NIST National Vulnerability Database
Mozilla Firefox < 116.0≥ 102.0 and < 102.14≥ 115.0 and < 115.1 Vulnerable NIST National Vulnerability Database
Mozilla Firefox < 116 Vulnerable CVE Program (cve.org) e CISA ADP
Mozilla Firefox ESR < 102.14< 115.1 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.3 CVSS 3.1 Medium 3.9 1.4 nvd@nist.gov via NIST National Vulnerability Database
5.3 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-346

Other CVEs with this weakness →

EPSS over time FIRST

Oct 23, 2026 → Oct 28, 2026 · 6 reading(s) · max 0.59%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · mozilla/firefox, mozilla/firefox esr
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 24, 2026
  • Affected products added · mozilla/firefox, debian/debian linux
    Oct 24, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.3
    Oct 24, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 24, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 24, 2026 · Alertas do Telegram
  • 2023
  • CVE published
    Aug 1, 2023 · mozilla

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 24, 2026 – Oct 24, 2026
  • 1× Official description updated · Oct 24, 2026 – Oct 24, 2026

References

13 on the record

Elsewhere on this site

Debian
every CVE for this vendor
CWE-346
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-111497 Google Brotli Unchecked Return Value Vulnerability KEV 7d
  • CVE-2026-106016 Mitigation bypass in the File Handling component 23d
  • CVE-2026-96869 Information disclosure in the Networking component Sep 29, 2026
  • CVE-2026-100832 Use-after-free in the Graphics: Canvas2D component Sep 29, 2026
  • CVE-2026-100829 Mitigation bypass in the DOM: Security component Sep 29, 2026
  • CVE-2026-100831 Use-after-free in the DOM: UI Events & Focus Handling component Sep 29, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2023-4045 is "Offscreen Canvas did not properly track cross-origin tainting, which could have been used to...", rated Medium. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.59% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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