VulnSocial

CVE-2026-45372Disclosure(yhirose / cpp-httplib)

LOWCVSS 9.9 · CRITICAL

Exploitation ongoing with high activity in latest observed window (1 mentions)

Immediate actions

  • Prioritize remediation for yhirose cpp-httplib systems immediately
  • Assume compromise if assets are exposed
  • Track advisory updates for patch or workaround availability

Recommended action window: Immediate (within 24h)

NVD description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (is_field_value) is run before decoding, so encoded %0D%0A passes the check and is then expanded to a literal \r\n byte pair inside the stored header value. This vulnerability is fixed in 0.44.0.

yhirose CVEsBack to dashboard
3.5/ 10 priority

Sources & remediation

Exploit / PoC references
Weakness type (CWE)
CWE-93CWE-444

Priority

LOW

Exploitation

ACTIVE

PoC

YES

Patch

NONE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • cpp-httplib

Threat summary

  • Active exploitation appears in 1 classified signals
  • 3 mentions across 3 observed days
  • Momentum state: stable

What's happening

  • Active exploitation reported across 1 signal
  • Disclosure: 1 classified signal
  • General: 1 classified signal
  • Peaked 2d ago at 1 mentions (2026-05-29); latest day: 1
  • 3 total mentions across 3 days

Affected systems

Vendors
yhirose
Products
cpp-httplib

Deep dive

Activity timeline3 mentions / 3d
00111Mentions · 2026-05-29: 1Mentions · 2026-05-30: 1Mentions · 2026-06-19: 1Active Exploitation · 2026-05-30: 105-2905-3006-19
Signal classification3 categories
Disclosure
133.3%
Active Exploitation
133.3%
General
133.3%
Referenced assets3 URLs
Classification over time
DateTotalLabels
2026-05-291
Disclosure1
2026-05-301
Active Exploitation1
2026-06-191
General1
Full discourse3 posts
  • IntegSec@integ_sec
    General

    CVE-2026-45372: Cpp-Httplib Header Injection Vulnerability - What It Means for Your Business and How to Respond https://hubs.li/Q04m0_v_0

    Post summary

    The text merely lists the CVE with a headline suggesting a general overview; it does not contain evidence of a PoC, exploit, active exploitation, patch, or technical details.

    0000026
    31 followersView on X
  • VulDB 🛡@vuldb
    Active Exploitation

    A lot of offensive activities were identified targeting yhirose cpp-httplib (CVE-2026-45372) https://vuldb.com/vuln/367381/cti

    Post summary

    The text indicates that CVE-2026-45372 is currently being exploited by numerous actors, with no available PoC, patch, or technical details disclosed here.

    0000054
    2.2K followersView on X
  • CVE@CVEnew
    Disclosure

    CVE-2026-45372 cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies pe… https://www.cve.org/CVERecord?id=CVE-2026-45372

    Post summary

    The post references CVE‑2026‑45372 and notes a parsing issue in cpp‑httplib versions before 0.44.0, but provides no further technical details, exploit resources, or mitigation steps.

    00000130
    57.5K followersView on X
CPE platform detail1 entries

1 of 1 entries

PartVendorProductVersionTarget SWTarget HW
Appyhirosecpp-httplib---

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