CVE-2021-20177
A flaw was found in the Linux kernel's implementation of string matching within a packet. A privileged user (with root or CAP_NET_ADMIN) when inserting iptables rules could insert a rule which can
02 Description
A flaw was found in the Linux kernel's implementation of string matching within a packet. A privileged user (with root or CAP_NET_ADMIN) when inserting iptables rules could insert a rule which can
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
- 0.28% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 20.6% of scored records. A rank, not a probability.
- NVD base score
- 4.4 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
- 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
- 2021-05-26 20:48Z5 YR AGO
- Last updated
- 2024-08-03 17:30Z2 YR AGO
- Reserved
- 2020-12-17
- Assigning CNA
- redhat
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- CWE-125Out-of-bounds ReadBase
- Data version
- 5.1
- Document digest
- 61aad8b8d101241eef0bacca16978fc65e7882dd975e4855e553cd57326eca40
05 Affected products
06 References
- bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=1914719
07 Fixed in
Arch Linux
- linux-lts Fixed in 5.4.81-1
Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.
Debian 12
- linux Fixed in 5.5.13-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- linux Fixed in 5.5.13-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- linux Fixed in 5.5.13-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 16.04 LTS
- linux-hwe-edge No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- linux-aws-5.0 No fix yet
- linux-aws-5.3 No fix yet
- linux-aws-5.4 Fixed in 5.4.0-1038.40~18.04.1
- linux-azure No fix yet
- linux-azure-5.3 No fix yet
- linux-azure-5.4 Fixed in 5.4.0-1040.42~18.04.1
- linux-azure-edge No fix yet
- linux-gcp No fix yet
- linux-gcp-5.3 No fix yet
- linux-gcp-5.4 Fixed in 5.4.0-1037.40~18.04.1
- linux-gcp-edge No fix yet
- linux-gke-5.4 Fixed in 5.4.0-1036.38~18.04.1
- linux-gkeop-5.4 Fixed in 5.4.0-1010.11~18.04.1
- linux-hwe No fix yet
- linux-hwe-5.4 Fixed in 5.4.0-66.74~18.04.2
- linux-hwe-edge No fix yet
- linux-oem No fix yet
- linux-oracle-5.0 No fix yet
- linux-oracle-5.3 No fix yet
- linux-oracle-5.4 Fixed in 5.4.0-1038.41~18.04.1
- linux-raspi-5.4 Fixed in 5.4.0-1029.32~18.04.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- linux Fixed in 5.4.0-66.74
- linux-aws Fixed in 5.4.0-1038.40
- linux-azure Fixed in 5.4.0-1040.42
- linux-gcp Fixed in 5.4.0-1037.40
- linux-gke Fixed in 5.4.0-1036.38
- linux-gkeop Fixed in 5.4.0-1010.11
- linux-kvm Fixed in 5.4.0-1033.34
- linux-oracle Fixed in 5.4.0-1038.41
- linux-raspi Fixed in 5.4.0-1029.32
- linux-raspi2 No fix yet
- linux-riscv No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- linux-intel-iot-realtime No fix yet
- linux-realtime No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 24.04 LTS
- linux-raspi-realtime No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro FIPS-updates 20.04 LTS
- linux-aws-fips Fixed in 5.4.0-1069.73+fips2Available with Ubuntu Pro: https://ubuntu.com/pro
- linux-azure-fips Fixed in 5.4.0-1073.76+fips1Available with Ubuntu Pro: https://ubuntu.com/pro
- linux-gcp-fips Fixed in 5.4.0-1067.71~20.04.1Available with Ubuntu Pro: https://ubuntu.com/pro
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro FIPS 20.04 LTS
- linux-aws-fips No fix yet
- linux-azure-fips No fix yet
- linux-gcp-fips 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.