Medium
double free in curl_maprintf
Type: advisorySources: OSV
The libcurl API function called `curl_maprintf()` can be tricked into doing a double free due to an unsafe `size_t` multiplication, on systems using 32-bit `size_t` variables. The function is also used internally in numerous situations. The function doubles an allocated memory area with realloc() and allows the size to wrap and become zero and when doing so realloc() returns NULL *and* frees the memory - in contrary to normal realloc() fails where it only returns NULL - causing libcurl to free the memory *again* in the error path. Systems with 64-bit versions of the `size_t` type are not affected by this issue. This behavior can be triggered using the publicly exposed function.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2016-8618
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 16:54 UTC · Revision 1
Source evidence
The libcurl API function called `curl_maprintf()` can be tricked into doing a double free due to an unsafe `size_t` multiplication, on systems using 32-bit `size_t` variables. The function is also used internally in numerous situations. The function doubles an allocated memory area with realloc() and allows the size to wrap and become zero and when doing so realloc() returns NULL *and* frees the memory - in contrary to normal realloc() fails where it only returns NULL - causing libcurl to free the memory *again* in the error path. Systems with 64-bit versions of the `size_t` type are not affected by this issue. This behavior can be triggered using the publicly exposed function.
osv:CURL-CVE-2016-8618
Complete source record
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"id": "d8e55d84199cd6a5a67751be664bf6a4653f104ad883ee259a09a8dfe2aca51f",
"url": "https://osv.dev/vulnerability/CURL-CVE-2016-8618",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "double free in curl_maprintf",
"summary": "The libcurl API function called `curl_maprintf()` can be tricked into doing a double free due to an unsafe `size_t` multiplication, on systems using 32-bit `size_t` variables. The function is also used internally in numerous situations. The function doubles an allocated memory area with realloc() and allows the size to wrap and become zero and when doing so realloc() returns NULL *and* frees the memory - in contrary to normal realloc() fails where it only returns NULL - causing libcurl to free the memory *again* in the error path. Systems with 64-bit versions of the `size_t` type are not affected by this issue. This behavior can be triggered using the publicly exposed function.",
"evidence": "osv:CURL-CVE-2016-8618",
"products": [],
"severity": "medium",
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"id": "CURL-CVE-2016-8618",
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"modified": "2026-10-27T01:28:33.364186189Z",
"provider": "osv",
"references": [],
"provider_metadata": {
"CWE": {
"id": "CWE-415",
"desc": "Double Free"
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