High Injection exploit reference

CVE-2025-59822 — Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section

Http4s is a Scala interface for HTTP services. In versions from 1.0.0-M1 to before 1.0.0-M45 and before 0.23.31, http4s is vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section. This vulnerability could enable attackers to bypass front-end servers security controls, launch targeted attacks against active users, and poison web caches. A pre-requisite for exploitation involves the web application being deployed behind a reverse-proxy that forwards trailer headers. This issue has been patched in versions 1.0.0-M45 and 0.23.31.

Published Sep 23, 2025 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+4
Technical severity (high)+6
CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.37%

ahead of 30% of scored CVEs · Oct 20, 2026

Affects

Http4s

Http4s and 3 more

CVSS base

7.5

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)
Maven Org.http4s:http4s-ember-core 2.12: fixed in version 0.23.31 — github.com (GitHub Security Advisories)
Maven Org.http4s:http4s-ember-core 2.13: fixed in version 0.23.31 — github.com (GitHub Security Advisories)
Maven Org.http4s:http4s-ember-core 2.13: fixed in version 1.0.0-M45 — github.com (GitHub Security Advisories)
Maven Org.http4s:http4s-ember-core 3: fixed in version 0.23.31 — github.com (GitHub Security Advisories)
Maven Org.http4s:http4s-ember-core 3: fixed in version 1.0.0-M45 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Http4s Http4s, Typelevel Http4s, Maven Org.http4s:http4s-ember-core 2.12…).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Http4s	Http4s	version >= 1.0.0-M1, < 1.0.0-M45version < 0.23.31	Vulnerable	CVE Program (cve.org) e CISA ADP
Typelevel	Http4s	version 1.0.0-milestone3version 1.0.0-milestone30version 1.0.0-milestone31version 1.0.0-milestone32version 1.0.0-milestone33version 1.0.0-milestone34version 1.0.0-milestone35version 1.0.0-milestone36 and 37 more version 1.0.0-milestone37version 1.0.0-milestone38version 1.0.0-milestone39version 1.0.0-milestone4version 1.0.0-milestone40version 1.0.0-milestone41version 1.0.0-milestone42version 1.0.0-milestone43version 1.0.0-milestone44version 1.0.0-milestone5version 1.0.0-milestone6version 1.0.0-milestone7version 1.0.0-milestone8version 1.0.0-milestone9version 1.0.0-milestone28< 0.23.31version 1.0.0-milestone1version 1.0.0-milestone10version 1.0.0-milestone11version 1.0.0-milestone12version 1.0.0-milestone13version 1.0.0-milestone14version 1.0.0-milestone15version 1.0.0-milestone16version 1.0.0-milestone17version 1.0.0-milestone18version 1.0.0-milestone19version 1.0.0-milestone2version 1.0.0-milestone20version 1.0.0-milestone21version 1.0.0-milestone22version 1.0.0-milestone23version 1.0.0-milestone24version 1.0.0-milestone25version 1.0.0-milestone26version 1.0.0-milestone27version 1.0.0-milestone29	Vulnerable	NIST National Vulnerability Database
Maven	Org.http4s:http4s-ember-core 2.12	< 0.23.31	Vulnerable	GitHub Security Advisories
Maven	Org.http4s:http4s-ember-core 2.13	< 0.23.31≥ 1.0.0-M1 and < 1.0.0-M45	Vulnerable	GitHub Security Advisories
Maven	Org.http4s:http4s-ember-core 3	< 0.23.31≥ 1.0.0-M1 and < 1.0.0-M45	Vulnerable	GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.3	CVSS 4.0	Medium	—	—	security-advisories@github.com via NIST National Vulnerability Database
6.3	CVSS 4.0	Medium	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
7.5	CVSS 3.1	High	3.9	3.6	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-444 · HTTP Request Smuggling

Other CVEs with this weakness →

EPSS over time FIRST

Oct 19, 2026 → Oct 20, 2026 · 2 reading(s) · max 0.37%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Look for parameters with command/query metacharacters and unexpected child processes of the service.

web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Fix documented
Oct 19, 2026 · GitHub Security Advisories
Affected products added · maven/org.http4s:http4s-ember-core 2.12, maven/org.http4s:http4s-ember-core 2.13, maven/org.http4s:http4s-ember-core 3
Oct 19, 2026 · GitHub Security Advisories
Affected products added · http4s/http4s
Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 19, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 19, 2026
Fix documented
Oct 19, 2026 · NIST National Vulnerability Database
Affected products added · typelevel/http4s
Oct 19, 2026 · NIST National Vulnerability Database
CVSS changed · 7.5
Oct 19, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 19, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 19, 2026 · Alertas do Telegram
2025
CVE published
Sep 23, 2025 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 19, 2026 – Oct 19, 2026
1× Official description updated · Oct 19, 2026 – Oct 19, 2026

References

4 on the record

github.com/http4s/http4s/security/advisories/GHSA-wcwh-7gfw-5wrr
Exploit, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/http4s/http4s/commit/dd518f7c967e5165813b8d4a48a82b8fab852d41
Patch, x_refsource_MISC, NIST National Vulnerability Database
github.com/advisories/GHSA-wcwh-7gfw-5wrr
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2025-59822
GitHub Security Advisories

Elsewhere on this site

Http4s
every CVE for this vendor

Injection
same class

CWE-444
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-88975 Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE Sep 15, 2026
High CVE-2026-69218 Http4s Ember HTTP/2: unbounded continuation frame accumulation Sep 15, 2026
High CVE-2026-69217 Http4s: Ember Server accepts duplicate Content-Length headers Sep 15, 2026
Medium CVE-2026-69215 Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin Sep 15, 2026
High CVE-2026-69210 Http4s: WebSocket decoder accepts negative length, causing infinite decode loop Sep 15, 2026
Medium CVE-2026-69206 Http4s: DigestAuth allows replay of captured requests Sep 15, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-59822 is "Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section", rated High. It affects Http4s (Http4s); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 0.37% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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