CVE-2023-30847
H2O vulnerable to read from uninitialized pointer in the reverse proxy handler
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
H2O vulnerable to read from uninitialized pointer in the reverse proxy handler
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
- Record
CVE-2023-30847- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-824
- Updated
- 2026-11-02
EUVDEUVD-2023-35199
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
- Record
EUVD-2023-35199- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-03
NVD
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
- Record
CVE-2023-30847- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-824
- Updated
- 2026-11-02
OSV
H2O vulnerable to read from uninitialized pointer in the reverse proxy handler
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
- Record
CVE-2023-30847- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-824
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2023-30847
H2O is an HTTP server. In versions 2.3.0-beta2 and prior, when the reverse proxy handler tries to processes a certain type of invalid HTTP request, it tries to build an upstream URL by reading from uninitialized pointer. This behavior can lead to crashes or leak of information to back end HTTP servers. Pull request number 3229 fixes the issue. The pull request has been merged to the master branch in commit f010336. Users should upgrade to commit f010336 or later.
- Record
UBUNTU-CVE-2023-30847- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
h2oUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 2.2.3+dfsg-22.2.4+dfsg-12.2.4+dfsg-1build12.2.4+dfsg-1ubuntu0.1~esm2 |
None known |
h2oUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 2.2.5+dfsg2-32.2.5+dfsg2-3build12.2.5+dfsg2-3ubuntu0.1~esm1 |
None known |
h2oUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 2.2.5+dfsg2-62.2.5+dfsg2-6.12.2.5+dfsg2-6.1ubuntu12.2.5+dfsg2-6.1ubuntu22.2.5+dfsg2-6.1ubuntu2+esm1 |
None known |
h2oUbuntu:24.04:LTS |
All versions, plus listed versions 2.2.5+dfsg2-72.2.5+dfsg2-82.2.5+dfsg2-8.1ubuntu12.2.5+dfsg2-8.1ubuntu22.2.5+dfsg2-8.1ubuntu3 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-30847 is a high vulnerability (CVSS 8.2) in Dena H2o, published April 27, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.90%, the 59th percentile. No source names a fixed version.
References
github.com/h2o/h2o/security/advisories/GHSA-p5hj-phwj-hrvx
nvd.nist.gov/vuln/detail/CVE-2023-30847
ubuntu.com/security/CVE-2023-30847
cve.org/CVERecord?id=CVE-2023-30847