Tenable.sc update for Apache HTTP Server
| Risk | High |
| Patch available | YES |
| Number of vulnerabilities | 3 |
| CVE-ID | CVE-2021-33193 CVE-2021-34798 CVE-2021-40438 |
| CWE-ID | CWE-444 CWE-476 CWE-918 |
| Exploitation vector | Network |
| Public exploit | Vulnerability #3 is being exploited in the wild. |
| Vulnerable software Subscribe |
Tenable.sc Server applications / DLP, anti-spam, sniffers |
| Vendor | Tenable Network Security |
Security Bulletin
This security bulletin contains information about 3 vulnerabilities.
1) Inconsistent interpretation of HTTP requests
EUVDB-ID: #VU56474
Risk: Medium
CVSSv3.1: 6.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-33193
CWE-ID:
CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to preform HTTP/2 request smuggling attacks.
The vulnerability exists due to improper validation of HTTP/2 requests in mod_proxy in Apache HTTP Server. A remote attacker can send a specially crafted HTTP/2 request to the server and smuggle arbitrary HTTP headers.
Successful exploitation of vulnerability may allow an attacker to poison web server cache and perform phishing attacks.
MitigationInstall update from vendor's website.
Vulnerable software versionsTenable.sc: 5.16.0 - 5.19.1
External linkshttp://www.tenable.com/security/tns-2021-17
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
2) NULL pointer dereference
EUVDB-ID: #VU56681
Risk: Medium
CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-34798
CWE-ID:
CWE-476 - NULL Pointer Dereference
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a NULL pointer dereference error. A remote attacker can send a specially crafted HTTP request to the affected web server and perform a denial of service (DoS) attack.
MitigationInstall update from vendor's website.
Vulnerable software versionsTenable.sc: 5.16.0 - 5.19.1
External linkshttp://www.tenable.com/security/tns-2021-17
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
3) Server-Side Request Forgery (SSRF)
EUVDB-ID: #VU56678
Risk: High
CVSSv3.1: 8.9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N/E:H/RL:O/RC:C]
CVE-ID: CVE-2021-40438
CWE-ID:
CWE-918 - Server-Side Request Forgery (SSRF)
Exploit availability: Yes
DescriptionThe disclosed vulnerability allows a remote attacker to perform SSRF attacks.
The vulnerability exists due to insufficient validation of user-supplied input within the mod_proxy module in Apache HTTP Server. A remote attacker can send a specially crafted HTTP request with a chosen uri-path and trick the web server to initiate requests to arbitrary systems.
Successful exploitation of this vulnerability may allow a remote attacker gain access to sensitive data, located in the local network or send malicious requests to other servers from the vulnerable system.
MitigationInstall update from vendor's website.
Vulnerable software versionsTenable.sc: 5.16.0 - 5.19.1
External linkshttp://www.tenable.com/security/tns-2021-17
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
Yes. This vulnerability is being exploited in the wild.
