CVE-2021-33909
fs/seq_file.c in the Linux kernel 3.16 through 5.13.x before 5.13.4 does not properly restrict seq buffer allocations, leading to an integer overflow, an Out-of-bounds Write, and escalation to root by an unprivileged user, aka CID-8cae8cd89f05.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (9.73%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
fs/seq_file.c in the Linux kernel 3.16 through 5.13.x before 5.13.4 does not properly restrict seq buffer allocations, leading to an integer overflow, an Out-of-bounds Write, and escalation to root by an unprivileged user, aka CID-8cae8cd89f05.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 9.73% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-190, CWE-787
- Affected
- linux/linux kernel · fedoraproject/fedora · debian/debian linux · netapp/hci management node · netapp/solidfire · oracle/communications session border controller · sonicwall/sma1000 firmware
- Source
- cve@mitre.org
EPSS 9.7% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://packetstormsecurity.com/files/163621/Sequoia-A-Deep-Root-In-Linuxs-Filesystem-Layer.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/163671/Kernel-Live-Patch-Security-Notice-LSN-0079-1.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlThird Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2021/07/22/7Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/25/10Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/17/2Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/17/4Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/21/1Mailing List, Third Party Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4Mailing List, Patch, Vendor Advisory
- https://github.com/torvalds/linux/commit/8cae8cd89f05f6de223d63e6d15e31c8ba9cf53bPatch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/07/msg00014.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/07/msg00015.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2021/07/msg00016.htmlMailing List, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z4UHHIGISO3FVRF4CQNJS4IKA25ATSFU/
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2022-0015Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210819-0004/Third Party Advisory
- https://www.debian.org/security/2021/dsa-4941Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/07/20/1Exploit, Mailing List, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- http://packetstormsecurity.com/files/163621/Sequoia-A-Deep-Root-In-Linuxs-Filesystem-Layer.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/163671/Kernel-Live-Patch-Security-Notice-LSN-0079-1.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.htmlThird Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083-1.htmlThird Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2021/07/22/7Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/25/10Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/17/2Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/17/4Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/09/21/1Mailing List, Third Party Advisory
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4Mailing List, Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.