Incorrect boundary conditions in the Graphics: CanvasWebGL component
Affects Mozilla Firefox and Thunderbird; the listed fix is in Firefox 160, and no Thunderbird fix version is given.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in Firefox 160
- Who is exposed
- Specific setups only
Do first: Upgrade to a fixed version: Firefox 160.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 22/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Mozilla Firefox has a flaw in its Graphics: CanvasWebGL component caused by incorrect boundary conditions. The available information does not describe what an attacker could gain or how they would reach the flaw, and it has been fixed in a newer release.
Read the original description
Incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 160 and Thunderbird 160.
Who should check
Teams running Mozilla Firefox or Thunderbird builds older than version 160.
cve.now Index
- Exploitation0/40No signal
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.8/10CVSS 8.8, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 72 if added to CISA KEV
- Would score about 67 if CISA's SSVC rates exploitation active
What to do
Upgrade to a fixed version: Firefox 160.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-124852 (Incorrect boundary conditions in the Graphics: CanvasWebGL component), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-124852 (entry last updated 2026-11-10): Affected: - Mozilla Firefox: version range not reported - Mozilla Thunderbird: version range not reported Fixed versions: Firefox 160. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, a user action. CISA KEV: CVE-2026-124852 is not listed as of cve.now's last read. This KEV status is for CVE-2026-124852 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://bugzilla.mozilla.org/show_bug.cgi?id=2001244 - https://www.mozilla.org/security/advisories/mfsa2026-125/ - https://www.mozilla.org/security/advisories/mfsa2026-128/ - https://www.mozilla.org/en-US/security/advisories/mfsa2026-125/ Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-124852 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-124852.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Mozilla Firefox
Version range not reported
- Mozilla Thunderbird
Version range not reported
Evidence 5
Vendor advisory · 3
Establishes: Affected and fixed versions.
- Link
- Link
- Link
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-124852
Is CVE-2026-124852 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
How do I fix CVE-2026-124852?
Upgrade Firefox to version 160. No fixed Thunderbird version and no workaround are listed in the checked facts.Source: mozilla.org