CVE-2021-43541
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and
02 Description
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and
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
- 1.69% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 76.9% of scored records. A rank, not a probability.
- NVD base score
- 6.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Moderate. 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 21:20Z4 YR AGO
- Last updated
- 2024-08-04 04:03Z2 YR AGO
- Reserved
- 2021-11-08
- Assigning CNA
- mozilla
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- CWE-428Unquoted Search Path or ElementBase
- Data version
- 5.1
- Document digest
- ac680f2fdfbccdd514e80be0633d6e869fdb96a3ea8ec83adcec64384be9e650
05 Affected products
06 References
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-53/
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-54/
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-52/
- bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1696685
- www.debian.orgDSA-5026https://www.debian.org/security/2021/dsa-5026
- lists.debian.org[debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security updatehttps://lists.debian.org/debian-lts-announce/2021/12/msg00030.html
- www.debian.orgDSA-5034https://www.debian.org/security/2022/dsa-5034
- lists.debian.org[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security updatehttps://lists.debian.org/debian-lts-announce/2022/01/msg00001.html
- security.gentoo.orgGLSA-202202-03https://security.gentoo.org/glsa/202202-03
- security.gentoo.orgGLSA-202208-14https://security.gentoo.org/glsa/202208-14
07 Fixed in
AlmaLinux 8
- firefox Fixed in 91.4.0-1.el8_5.alma
- thunderbird Fixed
A version is affected if any line below covers it.
- Affected before 91.4.0-2.el8_5.alma
- Affected before 91.4.0-2.el8_5.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 95.0-1
- thunderbird Fixed in 91.4.0-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
CloudLinux 8
- firefox Fixed in 91.4.0-1.el8_5.alma
- thunderbird Fixed
A version is affected if any line below covers it.
- Affected before 91.4.0-2.el8_5.alma
- Affected before 91.4.0-2.el8_5.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 91.4.0esr-1
- thunderbird Fixed in 1:91.4.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- firefox-esr Fixed in 91.4.0esr-1
- thunderbird Fixed in 1:91.4.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- firefox-esr Fixed in 91.4.0esr-1
- thunderbird Fixed in 1:91.4.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- firefox Fixed in 95.0+build1-0ubuntu0.18.04.1
- 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 95.0+build1-0ubuntu0.20.04.1
- 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 95.0+build1-0ubuntu1
- mozjs78 No fix yet
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.