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No exploitation reportedFix available

CVE-2026-33636

No exploitation reported by the sources we read.

  • Published2026-03-26
  • Fixed in1.6.56
  • WeaknessCWE-125 · CWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.

Timeline

dates in UTC
  1. 2026-03-2617:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-33636?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-33636?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Libpng
BranchAffectedFixed in
1.6≥ 1.6.36, < 1.6.561.6.56

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • firefoxAlmaLinux:10all versions · fixed in 140.9.1-1.el10_1
  • firefoxAlmaLinux:9all versions · fixed in 140.9.1-1.el9_7.alma.1and 2 other packages
  • firefoxAlmaLinux:8all versions · fixed in 140.9.1-1.el8_10.alma.1and 1 other package
  • java-25-openjdkAlmaLinux:10all versions · fixed in 1:25.0.3.0.9-1.el10_2and 25 other packages
  • java-25-openjdkAlmaLinux:9all versions · fixed in 1:25.0.3.0.9-1.el9.alma.1and 25 other packages
  • libpngAlmaLinux:10all versions · fixed in 2:1.6.40-11.el10_2.1and 1 other package
  • libpngAlmaLinux:10all versions · fixed in 2:1.6.40-8.el10_1.3and 1 other package
  • libpngAlmaLinux:9all versions · fixed in 2:1.6.37-12.el9_7.3and 1 other package

2 more package ranges on OSV.dev

Full record on NVD

Fix

  1. Update Libpng to 1.6.56

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionnone2026-03-26
  • OpenCVESSVC decisionnone—
  • CNACVSS 3.17.6read 2026-10-23
  • CNAweakness (CWE)CWE-125, CWE-787read 2026-10-23
  • FIRST EPSSEPSS score0.4 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
Published
2026-03-26
Last Modified
2026-06-17
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-33636?

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.

Is CVE-2026-33636 actively exploited?

Active exploitation of CVE-2026-33636 has not been confirmed. Its EPSS score was 0.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-33636?

CVE-2026-33636 has a CVSS v3 base score of 7.6 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H.

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