{ "document": { "aggregate_severity": { "text": "Important" }, "category": "csaf_security_advisory", "csaf_version": "2.0", "distribution": { "text": "TuxCare License Agreement", "tlp": { "label": "WHITE", "url": "https://www.first.org/tlp/" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Cloud Linux Inc. and provide a link to the original.", "title": "Terms of Use" }, { "category": "details", "text": "* SECURITY UPDATE: out-of-bounds read/write in ARM NEON palette expansion\n - debian/patches/CVE-2026-33636.patch: restrict the NEON loop in\n png_do_expand_palette_rgba8_neon and png_do_expand_palette_rgb8_neon\n (arm/palette_neon_intrinsics.c) to full chunks only, so rows whose\n width is not a multiple of the chunk size no longer read or write\n past the row buffer\n - CVE-2026-33636", "title": "Details" } ], "publisher": { "category": "vendor", "contact_details": "https://tuxcare.com/contact/", "name": "TuxCare", "namespace": "https://tuxcare.com/" }, "references": [ { "category": "self", "summary": "https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319", "url": "https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319" }, { "category": "self", "summary": "Canonical URL", "url": "https://security.tuxcare.com/csaf/v2/els_os/ubuntu20.04els/advisories/2026/clsa-2026_1785937319.json" } ], "tracking": { "current_release_date": "2026-08-05T13:42:41Z", "generator": { "date": "2026-08-05T13:42:41Z", "engine": { "name": "pyCSAF" } }, "id": "CLSA-2026:1785937319", "initial_release_date": "2026-08-05T13:42:41Z", "revision_history": [ { "date": "2026-08-05T13:42:41Z", "number": "1", "summary": "Initial version" } ], "status": "final", "version": "1" }, "title": "Fix CVE(s): CVE-2026-33416, CVE-2026-33636" }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_name", "name": "Ubuntu 20.04", "product": { "name": "Ubuntu 20.04", "product_id": "Ubuntu-20", "product_identification_helper": { "cpe": "cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*" } } } ], "category": "product_family", "name": "Ubuntu" } ], "category": "vendor", "name": "Canonical Ltd." }, { "branches": [ { "branches": [ { "category": "product_version", "name": "libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "product": { "name": "libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "product_id": "libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng-dev@1.6.37-2%2Btuxcare.els4?arch=amd64" } } }, { "category": "product_version", "name": "libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "product": { "name": "libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "product_id": "libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng-tools@1.6.37-2%2Btuxcare.els4?arch=amd64" } } }, { "category": "product_version", "name": "libpng16-16-0:1.6.37-2+tuxcare.els4.amd64", "product": { "name": "libpng16-16-0:1.6.37-2+tuxcare.els4.amd64", "product_id": "libpng16-16-0:1.6.37-2+tuxcare.els4.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng16-16@1.6.37-2%2Btuxcare.els4?arch=amd64" } } }, { "category": "product_version", "name": "libpng16-16-0:1.6.37-2+tuxcare.els2.amd64", "product": { "name": "libpng16-16-0:1.6.37-2+tuxcare.els2.amd64", "product_id": "libpng16-16-0:1.6.37-2+tuxcare.els2.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng16-16@1.6.37-2%2Btuxcare.els2?arch=amd64" } } }, { "category": "product_version", "name": "libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "product": { "name": "libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "product_id": "libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng-dev@1.6.37-2%2Btuxcare.els2?arch=amd64" } } }, { "category": "product_version", "name": "libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "product": { "name": "libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "product_id": "libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "product_identification_helper": { "purl": "pkg:deb/tuxcare/libpng-tools@1.6.37-2%2Btuxcare.els2?arch=amd64" } } } ], "category": "architecture", "name": "amd64" } ], "category": "vendor", "name": "TuxCare" } ], "relationships": [ { "category": "default_component_of", "full_product_name": { "name": "libpng-dev-0:1.6.37-2+tuxcare.els4.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64" }, "product_reference": "libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "relates_to_product_reference": "Ubuntu-20" }, { "category": "default_component_of", "full_product_name": { "name": "libpng-tools-0:1.6.37-2+tuxcare.els4.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64" }, "product_reference": "libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "relates_to_product_reference": "Ubuntu-20" }, { "category": "default_component_of", "full_product_name": { "name": "libpng16-16-0:1.6.37-2+tuxcare.els4.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" }, "product_reference": "libpng16-16-0:1.6.37-2+tuxcare.els4.amd64", "relates_to_product_reference": "Ubuntu-20" }, { "category": "default_component_of", "full_product_name": { "name": "libpng16-16-0:1.6.37-2+tuxcare.els2.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els2.amd64" }, "product_reference": "libpng16-16-0:1.6.37-2+tuxcare.els2.amd64", "relates_to_product_reference": "Ubuntu-20" }, { "category": "default_component_of", "full_product_name": { "name": "libpng-dev-0:1.6.37-2+tuxcare.els2.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els2.amd64" }, "product_reference": "libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "relates_to_product_reference": "Ubuntu-20" }, { "category": "default_component_of", "full_product_name": { "name": "libpng-tools-0:1.6.37-2+tuxcare.els2.amd64 as a component of Ubuntu 20.04", "product_id": "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els2.amd64" }, "product_reference": "libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "relates_to_product_reference": "Ubuntu-20" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33416", "cwe": { "id": "CWE-416", "name": "Use After Free" }, "notes": [ { "category": "description", "text": "LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.", "title": "Vulnerability description" }, { "category": "general", "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.", "title": "CVSS score applicability" } ], "product_status": { "fixed": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ], "known_affected": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els2.amd64" ] }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://cve.tuxcare.com/els/cve/CVE-2026-33416" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb", "url": "https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667", "url": "https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25", "url": "https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1", "url": "https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/pull/824", "url": "https://github.com/pnggroup/libpng/pull/824" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j", "url": "https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j" } ], "release_date": "2026-03-26T17:16:00Z", "remediations": [ { "category": "vendor_fix", "date": "2026-08-05T13:42:01.751226Z", "details": "Details on how to apply the fix are available at: https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319", "product_ids": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ], "url": "https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319" }, { "category": "none_available", "date": "2026-03-26T17:16:00Z", "details": "Affected", "product_ids": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els2.amd64" ] } ], "scores": [ { "cvss_v3": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1" }, "products": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ] } ], "threats": [ { "category": "impact", "details": "Important" } ] }, { "cve": "CVE-2026-33636", "cwe": { "id": "CWE-125", "name": "Out-of-bounds Read" }, "notes": [ { "category": "description", "text": "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.", "title": "Vulnerability description" }, { "category": "general", "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.", "title": "CVSS score applicability" } ], "product_status": { "fixed": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ], "known_affected": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els2.amd64" ] }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://cve.tuxcare.com/els/cve/CVE-2026-33636" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/7734cda20cf1236aef60f3bbd2267c97bbb40869", "url": "https://github.com/pnggroup/libpng/commit/7734cda20cf1236aef60f3bbd2267c97bbb40869" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/commit/aba9f18eba870d14fb52c5ba5d73451349e339c3", "url": "https://github.com/pnggroup/libpng/commit/aba9f18eba870d14fb52c5ba5d73451349e339c3" }, { "category": "external", "summary": "https://github.com/pnggroup/libpng/security/advisories/GHSA-wjr5-c57x-95m2", "url": "https://github.com/pnggroup/libpng/security/advisories/GHSA-wjr5-c57x-95m2" } ], "release_date": "2026-03-26T17:16:00Z", "remediations": [ { "category": "vendor_fix", "date": "2026-08-05T13:42:01.751226Z", "details": "Details on how to apply the fix are available at: https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319", "product_ids": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ], "url": "https://cve.tuxcare.com/els/releases/CLSA-2026:1785937319" }, { "category": "none_available", "date": "2026-03-26T17:16:00Z", "details": "Affected", "product_ids": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els2.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els2.amd64" ] } ], "scores": [ { "cvss_v3": { "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.6, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H", "version": "3.1" }, "products": [ "Ubuntu-20:libpng-dev-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng-tools-0:1.6.37-2+tuxcare.els4.amd64", "Ubuntu-20:libpng16-16-0:1.6.37-2+tuxcare.els4.amd64" ] } ], "threats": [ { "category": "impact", "details": "Important" } ] } ] }