CVE-2026-45352

highpriority · track · 30EPSS 0.003 · 26 %ileEURUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.33% (26th) EPSS
CVSS 7.5 · high
Is it mine?
5 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

7.5
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.3–7.5

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6
v3.17.5highAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · security-advisories@github.comexploitability 3.9 · impact 1.4
v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-1285USCWE-1285USCWE-20USCWE-20USCWE-770USCWE-770US
04

affected products (5)

Products and version ranges known to be affected.

05

also known as (3)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bdunvdNVDCVE.orgMITRE
published 2026-05-29modified 2026-07-22
07

references (4)

External citations — patches, advisories, analysis.

scry

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