Pillow: Image.quantize() with empty palette leaks uninitialized stack memory
Severity and exploitation
KEV coverage does not rule out exploitation.
Assessment vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NSeverity
medium6.9CVSS measures technical severity, not the likelihood of an attack.
Known exploitation
Not listed in the checked CISA KEV catalog
Absence from CISA KEV does not rule out attacks.
Public exploit
Exploit reference published
Source-linked evidence; not proof of attacks in the wild or independent validation.
Remediation
Fix status not established
No structured fix or guidance is available here. Check the latest publisher advisory.
What this means
Pillow versions 9.1.0 to 13.0.0 can leak uninitialized stack memory when Image.quantize() uses an empty palette, potentially disclosing addresses and stack-canary data. An attacker controlling the palette image can obtain this information from a returned PNG or GIF. This issue is related to the use of an uninitialized variable.
Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.Attack conditions
No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.
Review supporting sources →Affected versions
Check the exact model, release, and any platform requirements against your installation.
python-pillow · GitHub_M
Pillow
1 range
python-pillow · GitHub_M
Pillow
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affected
>= 9.1.0, < 13.0.0
Other versions: unknown
What to do
Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.
No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.
cve.new guidance unless attributed to a publisher. This page does not inspect your installation.
Public exploit evidence
The sources identify public exploit references. We have not independently tested them; their availability does not establish exploitation in the wild.
python-pillow/Pillow · security/advisories/GHSA-rfgq-q3w2-pmv2 ↗Attributed to CISA-ADPOriginal source description
Read the full publisher description
Pillow is a Python imaging library. From 9.1.0 until 13.0.0, Pillow can disclose uninitialized stack memory when Image.quantize() uses an empty palette. ImagingPaletteCacheUpdate() leaves a local cache array uninitialized when the palette has zero entries, and the conversion path emits those bytes as output pixel indices. An attacker who controls the palette image can obtain stack contents from a returned PNG or GIF. This can disclose addresses and stack-canary data without an out-of-bounds access, memory corruption, or process crash. This issue is fixed in version 13.0.0.
References
3 sourcesInside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
CVE-2026-112898View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.
cve.new JSON →Underlying weaknesses
The source’s classification of what caused the vulnerability.
Contributing organizations · 2
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Timeline
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Source updated
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Last imported by cve.new
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What changed
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