CVE-2025-53629 | cpp-httplib Unbounded Memory Allocation in Chunked/No-Length Requests Vulnerability

Exp

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.23.0, incoming requests using Transfer-Encoding: chunked in the header can allocate memory arbitrarily in the server, potentially leading to its exhaustion. This vulnerability is fixed in 0.23.0. NOTE: This vulnerability is related to CVE-2025-53628.

Published: 2025-07-10 Last update: 2025-08-06 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-53629 is rated High Exploit Risk (69.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.56%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-53629

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-53629

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-06 0.20% 0.56% +0.36%
2 2026-04-26 0.15% 0.20% +0.05%
3 2026-04-23 — 0.15% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-53629

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-53629

OS Trackers for CVE-2025-53629

vendor priority summary link
debian not yet assigned CVE-2025-53629 not yet assigned priority: Debian including 1 source packages (cpp-httplib), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 3, open 1. https://security-tracker.debian.org/tracker/CVE-2025-53629
suse high CVE-2025-53629 severity important: SUSE including 9 source package names (13.2-9.1:supportutils-3.2.10-1.1, 2.2.1-7.29:runc-1.3.3-slfo.1.1_1.1, …), 43 product×package rows across 31 product lines (Container suse/sl-micro/6.0/baremetal-os-container, Container suse/sl-micro/6.0/toolbox, … (31 product lines)): Fixed 42, First Fixed 1. https://www.suse.com/security/cve/CVE-2025-53629/
ubuntu medium CVE-2025-53629 medium priority: Ubuntu including 1 source packages (cpp-httplib), 5 status rows across 5 suites (jammy, noble, plucky, questing, upstream): needed 3, ignored 1, released 1. https://ubuntu.com/security/CVE-2025-53629

Affected software / configurations for CVE-2025-53629

Vendor Product Version Raw CPE
yhirose cpp-httplib < 0.23.0 cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*

References for CVE-2025-53629

cvelogic Threat Intelligence