CVE-2024-25622 | H2O ignores headers configuration directives

Exp

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The configuration directives provided by the headers handler allows users to modify the response headers being sent by h2o. The configuration file of h2o has scopes, and the inner scopes (e.g., path level) are expected to inherit the configuration defined in outer scopes (e.g., global level). However, if a header directive is used in the inner scope, all the definition in outer scopes are ignored. This can lead to headers not being modified as expected. Depending on the headers being added or removed unexpectedly, this behavior could lead to unexpected client behavior. This vulnerability is fixed in commit 123f5e2b65dcdba8f7ef659a00d24bd1249141be.

Published: 2024-10-11 Last update: 2024-11-12 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-25622 is rated Exploit Available (52.6/100): CVSS Low severity, with medium exploitation likelihood (EPSS 0.62%). 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-2024-25622

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

Exploit prediction scoring system (EPSS) score for CVE-2024-25622

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 2026-06-12 0.21% 0.62% +0.42%
2 2026-01-30 0.62% 0.21% -0.42%
3 2025-12-21 — 0.62% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-25622

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.1 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 1.4 [email protected]
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N 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:L)
A normal user session is enough; they don’t have to be admin.
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:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]

Weakness enumeration for CVE-2024-25622

OS Trackers for CVE-2024-25622

vendor priority summary link
alpine low CVE-2024-25622: 1 source package rows (h2o); 2 state rows across 1 repos (edge-community); fixed 0, open 2. https://security.alpinelinux.org/vuln/CVE-2024-25622
debian not yet assigned CVE-2024-25622 not yet assigned priority: Debian including 1 source packages (h2o), 2 status rows across 2 suites (bookworm, bullseye): open 2. https://security-tracker.debian.org/tracker/CVE-2024-25622
ubuntu medium CVE-2024-25622 medium priority: Ubuntu including 1 source packages (h2o), 8 status rows across 8 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream): needs-triage 5, ignored 2, DNE 1. https://ubuntu.com/security/CVE-2024-25622

Affected software / configurations for CVE-2024-25622

Vendor Product Version Raw CPE
dena h2o <= 2024-02-11 cpe:2.3:a:dena:h2o:*:*:*:*:*:*:*:*

References for CVE-2024-25622

cvelogic Threat Intelligence