CVE-2024-6197
High CVSS 7.5Published 2024-07-24 ยท last changed 2026-06-17
The fix
Microsoft fixes this in updatesKB5044277, KB5044273, KB5044280, KB5044285, KB5044284, KB5044281, KB5044288. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | 10.0.17763.6414 | KB5044277 | 2026-09-17 |
| Windows 10 Version 1809 for x64-based Systems | 10.0.17763.6414 | KB5044277 | 2026-09-17 |
| Windows 10 Version 21H2 for 32-bit Systems | 10.0.19044.5011 | KB5044273 | 2026-09-17 |
| Windows 10 Version 21H2 for ARM64-based Systems | 10.0.19044.5011 | KB5044273 | 2026-09-17 |
| Windows 10 Version 21H2 for x64-based Systems | 10.0.19044.5011 | KB5044273 | 2026-09-17 |
| Windows 10 Version 22H2 for 32-bit Systems | 10.0.19045.5011 | KB5044273 | 2026-09-17 |
| Windows 10 Version 22H2 for ARM64-based Systems | 10.0.19045.5011 | KB5044273 | 2026-09-17 |
| Windows 10 Version 22H2 for x64-based Systems | 10.0.19045.5011 | KB5044273 | 2026-09-17 |
| Windows 11 version 21H2 for ARM64-based Systems | 10.0.22000.3260 | KB5044280 | 2026-09-17 |
| Windows 11 version 21H2 for x64-based Systems | 10.0.22000.3260 | KB5044280 | 2026-09-17 |
| Windows 11 Version 22H2 for ARM64-based Systems | 10.0.22621.4317 | KB5044285 | 2026-09-17 |
| Windows 11 Version 22H2 for x64-based Systems | 10.0.22621.4317 | KB5044285 | 2026-09-17 |
| Windows 11 Version 23H2 for ARM64-based Systems | 10.0.22631.4317 | KB5044285 | 2026-09-17 |
| Windows 11 Version 23H2 for x64-based Systems | 10.0.22631.4317 | KB5044285 | 2026-09-17 |
| Windows 11 Version 24H2 for ARM64-based Systems | 10.0.26100.2033 | KB5044284 | 2026-09-17 |
| Windows 11 Version 24H2 for x64-based Systems | 10.0.26100.2033 | KB5044284 | 2026-09-17 |
| Windows Server 2019 | 10.0.17763.6414 | KB5044277 | 2026-09-17 |
| Windows Server 2019 (Server Core installation) | 10.0.17763.6414 | KB5044277 | 2026-09-17 |
| Windows Server 2022 | 10.0.20348.2762 | KB5044281 | 2026-09-17 |
| Windows Server 2022, 23H2 Edition (Server Core installation) | 10.0.25398.1189 | KB5044288 | 2026-09-17 |
| Windows Server 2022 (Server Core installation) | 10.0.20348.2762 | KB5044281 | 2026-09-17 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
libcurl's ASN1 parser has this utf8asn1str() function used for parsing an ASN.1 UTF-8 string. Itcan detect an invalid field and return error. Unfortunately, when doing so it also invokes `free()` on a 4 byte localstack buffer. Most modern malloc implementations detect this error and immediately abort. Some however accept the input pointer and add that memory to its list of available chunks. This leads to the overwriting of nearby stack memory. The content of the overwrite is decided by the `free()` implementation; likely to be memory pointers and a set of flags. The most likely outcome of exploting this flaw is a crash, although it cannot be ruled out that more serious results can be had in special circumstances.
Sources
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H