CVE-2026-33582: Apache Answer TIFF Image DoS Vulnerability (Medium CVSS 6.5)

Technical summary

CVE-2026-33582 is an unrestricted file upload vulnerability (CWE-434) in Apache Answer affecting versions up to and including 2.0.0. The flaw resides in image decoding logic where a malicious TIFF file can be uploaded by an authenticated user to exhaust server memory during decompression or processing, resulting in an out-of-memory condition and process termination. The vulnerability requires valid authentication and network access but no user interaction beyond file submission.

Business impact

This vulnerability enables authenticated attackers to perform denial-of-service attacks against Apache Answer deployments. An attacker with valid credentials can repeatedly upload malicious TIFF files to exhaust server memory and crash the application, disrupting service availability for legitimate users. In multi-tenant or community-driven Answer instances, this creates risk of abuse by compromised or malicious user accounts.

Affected systems

Apache Answer versions 2.0.0 and earlier are affected. Organizations running Apache Answer should verify their installed version immediately. The vulnerability does not affect Apache Answer 2.0.1 and later, where the issue has been patched.

Exploitability

Exploitation requires valid user authentication to Apache Answer, placing this in the 'authenticated' threat model. No special tools, elevated privileges, or user interaction are needed beyond normal file upload functionality. The attack is straightforward to execute once credentials are obtained, making it a practical concern in environments with many user accounts or weak access controls.

Remediation

Upgrade Apache Answer to version 2.0.1 or later as the primary remediation. Organizations unable to patch immediately should implement network-level access controls to restrict who can authenticate to Answer instances, reduce the number of user accounts with upload privileges, and monitor server resource consumption for abnormal memory spikes that may indicate exploitation attempts.

Patch guidance

Apache Answer 2.0.1 contains the fix for this vulnerability. Administrators should plan and execute an upgrade to 2.0.1 or a later version at their earliest opportunity. Verify the upgrade by checking the application version in the web interface or configuration files post-deployment. Test file upload functionality after patching to confirm normal operation.

Detection guidance

Monitor Apache Answer server logs for repeated failed or suspicious file upload attempts, particularly TIFF images. Watch for unexpected memory utilization spikes or out-of-memory errors in application logs corresponding to file upload activity. Network monitoring can flag repeated large file uploads from the same authenticated user. Consider alerting on process restarts or crashes of the Answer service process.

Why prioritize this

Although the CVSS score is 6.5 (Medium), prioritization depends on your deployment context. If Answer is public-facing or supports many user accounts, treat this as higher priority due to ease of exploitation by any authenticated user. If Answer is internal-only with strictly controlled access, lower priority is acceptable. The lack of KEV designation and absence of confidentiality or integrity impact support a measured approach, but availability is critical for collaboration tools.

Risk score, explained

CVSS 3.1 score of 6.5 reflects: attack vector Network (remotely exploitable), low complexity (straightforward crafted file), requires Low privileges (authenticated user), no special user interaction, and results in High severity to availability (service crash). The score does not account for business context—organizations depending heavily on Answer for Q&A or knowledge sharing should weight availability impact more heavily.

Frequently asked questions