CVE-2026-81685 in openssl_encrypt
Summary
by MITRE • 08/27/2026
openssl_encrypt versions before 1.4.9 fail to sanitize recovery-slot metadata in the desktop GUI, allowing attackers to inject control characters and line separators into the irreversible-removal confirmation dialog. Attackers can craft encrypted files with malicious slot identifiers containing bidi overrides or line-separator characters to forge warning text and deceive users during file removal operations.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/27/2026
The vulnerability identified in openssl_encrypt versions prior to 1.4.9 represents a critical input validation failure within the desktop graphical user interface, specifically concerning the handling of recovery-slot metadata. This flaw stems from insufficient sanitization of data retrieved or processed for display during irreversible removal operations. When users initiate the deletion of encrypted files that rely on specific recovery slots, the application retrieves associated metadata to present confirmation dialogs and warning messages. The core technical deficiency lies in the failure to filter control characters, particularly bidirectional text overrides such as Unicode U+202E (RIGHT-TO-LEFT OVERRIDE) or line separators like U+2028, from these slot identifiers before they are rendered in the user interface. This lack of sanitization allows an attacker who can influence the content of encrypted files to inject malicious formatting codes directly into the confirmation prompts displayed to the victim.
From a technical perspective, this vulnerability exploits the way modern operating systems and UI frameworks handle bidirectional text rendering. By injecting right-to-left override characters or other control sequences into the slot identifier metadata, an attacker can manipulate the visual ordering of text on the screen without altering the underlying logical string structure in a detectable manner for simple validation checks. For instance, an attacker might craft a file where the recovery-slot ID contains hidden control characters that reorder the warning message. A typical confirmation dialog stating "Are you sure you want to delete this encrypted file?" could be visually transformed into something entirely different, such as "Are you sure you want to keep this file?" or other deceptive text, depending on how the injected characters interact with the surrounding UI elements. This technique is a form of injection attack that targets the presentation layer rather than the backend logic directly, leveraging the trust users place in visual cues provided by trusted applications.
The operational impact of this vulnerability is significant due to its potential for social engineering and user deception. Since the manipulation occurs within the irreversible-removal confirmation dialog, it directly affects a high-stakes decision point where data loss is permanent. An attacker who has previously gained access to create or modify encrypted files with specific recovery-slot metadata can lure victims into accidentally deleting their own data by presenting a forged warning that suggests no action will be taken or implies safety when deletion is imminent. This undermines the integrity of the user interface and erodes trust in the encryption software, as users may become hesitant to rely on confirmation dialogs for critical operations. The attack does not require remote code execution but instead focuses on causing data loss through deception, which can have severe consequences for individuals relying on these files for personal or professional purposes.
This vulnerability aligns with CWE-79, Improper Neutralization of Input During Web Page Generation, although in this context it applies to desktop GUI generation rather than web pages specifically. It also relates closely to CWE-838, Inconsistent Interpretation of Inputs when used as the basis for decision-making, where the visual representation differs from the logical intent due to untrusted input influencing rendering logic. Furthermore, within the MITRE ATT&CK framework, this behavior corresponds to techniques involving UI Redressing or Deceptive Content Injection, which are often categorized under Initial Access or Execution phases depending on whether further actions are triggered by the user's response to the deceptive prompt. The attack vector is typically local if the attacker must create the malicious encrypted file on the victim's machine, but could be remote if the vulnerability allows for exploitation via downloaded files opened in the application.
Mitigation strategies primarily involve updating openssl_encrypt to version 1.4.9 or later, where this input validation flaw has been addressed by implementing strict sanitization of recovery-slot metadata before it is passed to UI components. Developers should ensure that all user-supplied data intended for display undergoes rigorous filtering to remove control characters and non-printable symbols that could alter text rendering behavior. Additionally, employing allowlist-based validation for slot identifiers can prevent the injection of unexpected character classes. For users unable to update immediately, caution is advised when opening encrypted files from untrusted sources, particularly those involving recovery-slot operations. Security awareness training should emphasize verifying the exact wording and layout of confirmation dialogs before confirming irreversible actions, although this is a secondary defense given that automated patching remains the most effective solution.