synced 4 MIN AGO
01 Record

CVE-2021-38503

The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability

UnratedPUBLISHEDCNA: mozilla
CNA base scoreUnratedNo CNA CVSS vector
View raw JSON

02 Description

The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability

03 Exploitation and scoring

Exploitation
Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision
Not assessed by CISA
EPSS probability
4.11% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 90.4% of scored records. A rank, not a probability.
NVD base score
10.0 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2021-12-08 21:22Z4 YR AGO
Last updated
2024-08-04 01:44Z2 YR AGO
Reserved
2021-08-10
Assigning CNA
mozilla
Record state
PUBLISHED
Severity
Not rated by the issuing CNA
CNA CVSS vector
Not published by the issuing CNA
Weaknesses
  • CWE-863Incorrect AuthorizationClass
  • CWE-732Incorrect Permission Assignment for Critical ResourceClass
Data version
5.1
Document digest
129a82f033b8cdf26fd12ef927e0f7331b69b2fbbbeaaeca9bf53972f5c7c5a3

05 Affected products

VendorProductVersionsPlatforms
MozillaFirefox< 94—
MozillaThunderbird< 91.3—
MozillaFirefox ESR< 91.3—

06 References

07 Fixed in

AlmaLinux 8

  • firefox
    Fixed in 91.3.0-1.el8_4.alma
  • thunderbird
    Fixed

    A version is affected if any line below covers it.

    • Affected before 91.3.0-2.el8_4.alma
    • Affected before 91.3.0-2.el8_4.alma.plus

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Arch Linux

  • firefox
    Fixed in 94.0-1
  • thunderbird
    Fixed in 91.3.0-1

Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.

CloudLinux 8

  • firefox
    Fixed in 91.3.0-1.el8_4.alma
  • thunderbird
    Fixed

    A version is affected if any line below covers it.

    • Affected before 91.3.0-2.el8_4.alma
    • Affected before 91.3.0-2.el8_4.alma.plus

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • firefox-esr
    Fixed in 91.3.0esr-1
  • thunderbird
    Fixed in 1:91.3.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • firefox-esr
    Fixed in 91.3.0esr-1
  • thunderbird
    Fixed in 1:91.3.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • firefox-esr
    Fixed in 91.3.0esr-1
  • thunderbird
    Fixed in 1:91.3.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • firefox
    Fixed in 94.0+build3-0ubuntu0.18.04.1
  • mozjs38
    No fix yet
  • mozjs52
    No fix yet
  • thunderbird
    Fixed in 1:91.5.0+build1-0ubuntu0.18.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • firefox
    Fixed in 94.0+build3-0ubuntu0.20.04.1
  • mozjs52
    No fix yet
  • mozjs68
    No fix yet
  • thunderbird
    Fixed in 1:91.5.0+build1-0ubuntu0.20.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • firefox
    Fixed in 94.0+build3-0ubuntu1
  • mozjs78
    No fix yet
  • thunderbird
    Fixed in 1:91.3.1+build1-0ubuntu1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.