Upstream information
Description
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul("-2", ..., 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE). The library's only guard (line 12833) rejects ULONG_MAX (the result of "-1"), but any other negative value such as "-2" passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server's read loop consumes from the network. This vulnerability is fixed in 0.43.4.SUSE information
Overall state of this security issue: Pending
This issue is currently rated as having moderate severity.
| CVSS detail | CNA (GitHub) | SUSE |
|---|---|---|
| Base Score | 5.3 | 5.3 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| Attack Vector | Network | Network |
| Attack Complexity | Low | Low |
| Privileges Required | None | None |
| User Interaction | None | None |
| Scope | Unchanged | Unchanged |
| Confidentiality Impact | None | None |
| Integrity Impact | None | None |
| Availability Impact | Low | Low |
| CVSSv3 Version | 3.1 | 3.1 |
Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Server 16.0 | cpp-httplib | Affected |
| SUSE Linux Enterprise Server 16.1 | cpp-httplib | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | cpp-httplib | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | cpp-httplib | Affected |
| openSUSE Leap 16.0 | cpp-httplib | Affected |
SUSE Timeline for this CVE
CVE page created: Sat May 30 00:06:24 2026CVE page last modified: Mon Jun 1 11:30:12 2026