Raw vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-25646 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Libpng Libpng. Its CVSS base score is 8.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 42% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-25646 is an out-of-bounds read vulnerability in the LIBPNG reference library, which applications use to read, create, and manipulate PNG raster image files. In versions prior to 1.6.55, the png_set_quantize() API function mishandles certain palettes when called without a histogram and the number of colors exceeds twice the maximum supported by the user's display. This causes an infinite loop that reads past the end of a heap-allocated internal buffer. The triggering images are valid per the PNG specification. The vulnerability is associated with CWE-122 (heap-based buffer overflow) and CWE-126 (buffer over-read), earning a CVSS v3.1 base score of 8.1 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).
Remote attackers can exploit this vulnerability without privileges or user interaction by supplying a specially crafted PNG image to a vulnerable application that processes it via LIBPNG's png_set_quantize() function under the specified conditions. Successful exploitation leads to high-impact confidentiality, integrity, and availability consequences, potentially including information disclosure from out-of-bounds reads, memory corruption, or denial of service via the infinite loop and crash.
The vulnerability is fixed in LIBPNG version 1.6.55, as detailed in the project's GitHub security advisory (GHSA-g8hp-mq4h-rqm3) and the fixing commit (01d03b8453eb30ade759cd45c707e5a1c7277d88). Security practitioners should update to 1.6.55 or later and audit applications using LIBPNG for PNG palette quantization operations, per discussions on the oss-security mailing list.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7050
Vulnerability Data
LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. Prior to 1.6.55, an out-of-bounds read vulnerability exists in the png_set_quantize() API function. When the function is called with…
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no histogram and the number of colors in the palette is more than twice the maximum supported by the user's display, certain palettes will cause the function to enter into an infinite loop that reads past the end of an internal heap-allocated buffer. The images that trigger this vulnerability are valid per the PNG specification. This vulnerability is fixed in 1.6.55.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Process isolation limits the blast radius of an over-read to the compromised domain.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance can detect heap overflows before release.
Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.