Answer in brief
CVE-2021-47243 records a High severity (CVSS 7.1) vulnerability in sch_cake: Fix out of bounds when parsing TCP options and header. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc6:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <595897ef118d6fe66690c4fc5b572028c9da95b7 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <4cefa061fc63f4d2dff5ab4083f43857cd7a2335 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <3b491dd593d582ceeb27aa617600712a6bd14246 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <3371392c60e2685af30bd4547badd880f5df2b3f || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <ba91c49dedbde758ba0b72f57ac90b06ddf8e548 | 595897ef118d6fe66690c4fc5b572028c9da95b7, 4cefa061fc63f4d2dff5ab4083f43857cd7a2335, 3b491dd593d582ceeb27aa617600712a6bd14246, 3371392c60e2685af30bd4547badd880f5df2b3f, ba91c49dedbde758ba0b72f57ac90b06ddf8e548 |
| Linux/Linuxgeneric | 4.19 | Not reported |
Published upstream
May 21, 2024
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 4, 2026
In the Linux kernel, the following vulnerability has been resolved: sch_cake: Fix out of bounds when parsing TCP options and header The TCP option parser in cake qdisc (cake_get_tcpopt and cake_tcph_may_drop) could read one byte out of bounds. When the length is 1, the execution flow gets into the loop, reads one byte of the opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds the length of 1. This fix is inspired by commit 9609dad263f8 ("ipv4: tcp_input: fix stack out of bounds when parsing TCP options."). v2 changes: Added doff validation in cake_get_tcphdr to avoid parsing garbage as TCP header. Although it wasn't strictly an out-of-bounds access (memory was allocated), garbage values could be read where CAKE expected the TCP header if doff was smaller than 5.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2021-47243 records a High severity (CVSS 7.1) vulnerability in sch_cake: Fix out of bounds when parsing TCP options and header. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:5.13:rc6:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <595897ef118d6fe66690c4fc5b572028c9da95b7 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <4cefa061fc63f4d2dff5ab4083f43857cd7a2335 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <3b491dd593d582ceeb27aa617600712a6bd14246 || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <3371392c60e2685af30bd4547badd880f5df2b3f || >=8b7138814f29933898ecd31dfc83e35a30ee69f5 <ba91c49dedbde758ba0b72f57ac90b06ddf8e548 | 595897ef118d6fe66690c4fc5b572028c9da95b7, 4cefa061fc63f4d2dff5ab4083f43857cd7a2335, 3b491dd593d582ceeb27aa617600712a6bd14246, 3371392c60e2685af30bd4547badd880f5df2b3f, ba91c49dedbde758ba0b72f57ac90b06ddf8e548 |
| Linux/Linuxgeneric | 4.19 | Not reported |
Published upstream
May 21, 2024
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 4, 2026
In the Linux kernel, the following vulnerability has been resolved: sch_cake: Fix out of bounds when parsing TCP options and header The TCP option parser in cake qdisc (cake_get_tcpopt and cake_tcph_may_drop) could read one byte out of bounds. When the length is 1, the execution flow gets into the loop, reads one byte of the opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds the length of 1. This fix is inspired by commit 9609dad263f8 ("ipv4: tcp_input: fix stack out of bounds when parsing TCP options."). v2 changes: Added doff validation in cake_get_tcphdr to avoid parsing garbage as TCP header. Although it wasn't strictly an out-of-bounds access (memory was allocated), garbage values could be read where CAKE expected the TCP header if doff was smaller than 5.
Quoted source text, attributed separately from HOL analysis.