7.1 CVE-2026-33019
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1.
https://nvd.nist.gov/vuln/detail/CVE-2026-33019
Categories
CWE-125 : Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer. When an out-of-bounds read occurs, typically the product has already made a separate mistake, such as modifying an index or performing pointer arithmetic that produces an out-of-bounds address. Shorthand for "Out of bounds" read Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Use tools that are integrated duringcompilation to insert runtime error-checking mechanismsrelated to memory safety errors, such as AddressSanitizer(ASan) for C/C++ [REF-1518]. Use a language that provides appropriate memory abstractions. The reference implementation code for a Trusted Platform Module does not implement length checks on data, allowing for an attacker to read 2 bytes past the end of a buffer. Out-of-bounds read in IP stack used in embedded systems, as exploited in the wild per CISA KEV. Chain: "Heartbleed" bug receives an inconsistent length parameter (CWE-130) enabling an out-of-bounds read (CWE-126), returning memory that could include private cryptographic keys and other sensitive data. HTML conversion package has a buffer under-read, allowing a crash Chain: unexpected sign extension (CWE-194) leads to integer overflow (CWE-190), causing an out-of-bounds read (CWE-125) Chain: product does not handle when an input string is not NULL terminated (CWE-170), leading to buffer over-read (CWE-125) or heap-based buffer overflow (CWE-122). Chain: series of floating-point precision errors(CWE-1339) in a web browser rendering engine causes out-of-bounds read(CWE-125), giving access to cross-origin data out-of-bounds read due to improper length check packet with large number of specified elements cause out-of-bounds read. packet with large number of specified elements cause out-of-bounds read. out-of-bounds read, resultant from integer underflow large length value causes out-of-bounds read malformed image causes out-of-bounds read OS kernel trusts userland-supplied length value, allowing reading of sensitive information
References
134c704f-9b21-4f2e-91b3-4a467353bcc0
security-advisories@github.com
AFFECTED (from MITRE)
| Vendor |
Product |
Versions |
| saitoha |
libsixel |
|
| © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. |
CPE
REMEDIATION
EXPLOITS
Exploit-db.com
| id |
description |
date |
|
| No known exploits |
POC Github
Other Nist (github, ...)
CAPEC
Common Attack Pattern Enumerations and Classifications
| id |
description |
severity |
| 540 |
Overread Buffers
An adversary attacks a target by providing input that causes an application to read beyond the boundary of a defined buffer. This typically occurs when a value influencing where to start or stop reading is set to reflect positions outside of the valid memory location of the buffer. This type of attack may result in exposure of sensitive information, a system crash, or arbitrary code execution. [Identify target application] The adversary identifies a target application or program to perform the buffer overread on. Adversaries often look for applications that accept user input and that perform manual memory management. [Find attack vector] The adversary identifies an attack vector by looking for areas in the application where they can specify to read more data than is required. [Overread the buffer] The adversary provides input to the application that gets it to read past the bounds of a buffer, possibly revealing sensitive information that was not intended to be given to the adversary. |
High |
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