CVE-2021-43535
A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects
02 Description
A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects
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
- 1.14% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 66.6% of scored records. A rank, not a probability.
- NVD base score
- 8.8 (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: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 21:20Z4 YR AGO
- Last updated
- 2024-08-04 03:55Z2 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-416Use After FreeVariant
- Data version
- 5.1
- Document digest
- 319380f5cc395cd8a3a85ef4e008e81be6fe0fe8341a1a83625ed9f228f611f9
05 Affected products
06 References
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-43/
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-49/
- www.mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2021-50/
- bugzilla.mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1667102
- 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
07 Fixed in
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
- 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
- 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.
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.