CyberSecBulletin
CVE-2019-0211Exploited in the wildNVD status: Analyzed

Apache HTTP Server Privilege Escalation

Published Updated By the CyberSecBulletin desk

CVE-2019-0211 is a high-severity use after free vulnerability in Apache HTTP Server from Apache, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected Apache HTTP Server versions: 2.4.17 to 2.4.38. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Check which version of Apache HTTP Server you run against the affected versions below, and install the vendor's latest release.
  2. CISA's required action: Apply updates per vendor instructions.
  3. Read the advisory on packetstormsecurity.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
ApacheApache HTTP Server2.4.17 to 2.4.38Not stated
ApacheHTTP Server2.4.17 through 2.4.38Not stated
Fedora ProjectFedora28; 29; 30Not stated
CanonicalUbuntu Linux14.04; 16.04; 18.04; 18.10Not stated
DebianDebian Linux9.0Not stated
openSUSELeap15.0; 42.3Not stated
NetAppOncommand Unified ManagerNot specified in the recordNot stated
Red HatJboss Core Services1.0Not stated
Red HatOpenshift Container Platform3.11Not stated
Red HatOpenshift Container Platform For Power3.11_ppc64leNot stated
Red HatSoftware Collections1.0Not stated
Red HatEnterprise Linux8.0Not stated
Red HatEnterprise Linux EUS8.1; 8.2; 8.4; 8.6; 8.8Not stated
Red HatEnterprise Linux For Arm 648.0_aarch64Not stated
Red HatEnterprise Linux For Arm 64 EUS8.1_aarch64; 8.2_aarch64; 8.4_aarch64; 8.6_aarch64; 8.8_aarch64Not stated
Red HatEnterprise Linux For IBM Z Systems8.0_s390xNot stated
Red HatEnterprise Linux For IBM Z Systems EUS8.1_s390x; 8.2_s390x; 8.4_s390x; 8.6_s390x; 8.8_s390xNot stated
Red HatEnterprise Linux For Power Little Endian8.0_ppc64leNot stated
Red HatEnterprise Linux For Power Little Endian EUS8.1_ppc64le; 8.2_ppc64le; 8.4_ppc64le; 8.6_ppc64le; 8.8_ppc64leNot stated
Red HatEnterprise Linux Server AUS8.2; 8.4; 8.6Not stated
Red HatEnterprise Linux Server TUS8.2; 8.4; 8.6; 8.8Not stated
Red HatEnterprise Linux Update Services For SAP Solutions8.0; 8.1; 8.4; 8.6; 8.8Not stated
OracleCommunications Session Report Manager8.0.0; 8.1.0; 8.1.1; 8.2.0Not stated
OracleCommunications Session Route Manager8.0.0; 8.1.0; 8.1.1; 8.2.0Not stated
OracleEnterprise Manager Ops Center12.3.3; 12.4.0Not stated

Version data comes from the organisation that assigned the CVE; 2 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)
CVSS 2.07.2HighNVD

Official description

In Apache HTTP Server 2.4 releases 2.4.17 to 2.4.38, with MPM event, worker or prefork, code executing in less-privileged child processes or threads (including scripts executed by an in-process scripting interpreter) could execute arbitrary code with the privileges of the parent process (usually root) by manipulating the scoreboard. Non-Unix systems are not affected.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other references

Other vulnerabilities in Apache HTTP Server

All Apache HTTP Server vulnerabilities

Recent Use After Free vulnerabilities

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