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CVE-2023-6873· NVD / CVE Program· CNA mozilla

Memory safety bugs present in Firefox 120.

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.85% (FIRST EPSS); higher than 57.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: thunderbird (Debian:10) 1:115.6.0-1~deb10u1; thunderbird (Debian:11) 1:115.6.0-1~deb11u1; thunderbird (Debian:12) 1:115.6.0-1~deb12u1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to thunderbird (Debian:10) 1:115.6.0-1~deb10u1; thunderbird (Debian:11) 1:115.6.0-1~deb11u1; thunderbird (Debian:12) 1:115.6.0-1~deb12u1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Memory safety bugs present in Firefox 120. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 121.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Dec 19, 2023
Updated
Jun 17, 2026
EPSS
0.8% · 57th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mozillafirefox
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • debian debian linux11.0
  • debian debian linux12.0
  • mozilla firefoxbefore 121.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.

  • Mozilla Firefox

    • unspecified and later · before 121affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:10thunderbirdbefore 1:115.6.0-1~deb10u11:115.6.0-1~deb10u1
Debian:11thunderbirdbefore 1:115.6.0-1~deb11u11:115.6.0-1~deb11u1
Debian:12thunderbirdbefore 1:115.6.0-1~deb12u11:115.6.0-1~deb12u1
openSUSE:TumbleweedMozillaFirefoxbefore 121.0-1.1121.0-1.1

Same product

mozilla: all records

Other highest-scoring records for the same primary product.

  • CVE-2010-3765Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x befKEV
    94Now
  • CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV
    87Now
  • CVE-2015-4495The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypassKEV
    86Now

Published before and after this one in the same product

  • ← EarlierCVE-2023-6871Dec 19, 2023 · Under certain conditions, Firefox did not display a warning when a user attempted to navigate to a new protocol handler.
    17Monitor
  • ← EarlierCVE-2023-6872Dec 19, 2023 · Browser tab titles were being leaked by GNOME to system logs.
    26Monitor
  • Later →CVE-2024-0741Jan 23, 2024 · An out of bounds write in ANGLE could have allowed an attacker to corrupt memory leading to a potentially exploitable crash.
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:thunderbird1:115.6.0-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:MozillaFirefox121.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-0247385 days apartMemory safety bugs fixed in Firefox 134 and Thunderbird 134
    42Plan
  • CVE-2023-68560 days apartThe WebGL `DrawElementsInstanced` method was susceptible to a heap buffer overflow when used on systems with the Mesa VM driver.
    41Plan
  • CVE-2023-573055 days apartMemory safety bugs present in Firefox 118, Firefox ESR 115.3, and Thunderbird 115.3.
    39Monitor
  • CVE-2023-573155 days apartMemory safety bugs present in Firefox 118.
    39Monitor
  • CVE-2023-516883 days apartA compromised content process could have provided malicious data to `FilterNodeD2D1` resulting in an out-of-bounds write, leading to a poten
    39Monitor
  • CVE-2023-517683 days apartMemory safety bugs present in Firefox 117, Firefox ESR 115.2, and Thunderbird 115.2.
    39Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records