| Title | libvips 8.19.0(7fab325d2) Out-of-Bounds Read |
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| Description | In `libvips/conversion/unpremultiply.c`, function `vips_unpremultiply_build()` does not verify that user-provided `alpha_band` is smaller than `in->Bands`. In `vips_unpremultiply_gen()` (`UNPRE_MANY` path), `p[alpha_band]` and `q[alpha_band]` are accessed directly, leading to out-of-bounds memory access for oversized `--alpha-band` values. The issue is reachable via normal `vips unpremultiply` CLI usage and is reproducible with ASAN as `heap-buffer-overflow`. |
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| Source | ⚠️ https://github.com/libvips/libvips/issues/4881 |
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| User | Niebelungen (UID 95430) |
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| Submission | 02/15/2026 04:01 PM (2 months ago) |
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| Moderation | 02/26/2026 05:33 PM (11 days later) |
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| Status | Accepted |
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| VulDB entry | 348011 [libvips 8.19.0 unpremultiply.c vips_unpremultiply_build alpha_band out-of-bounds] |
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| Points | 20 |
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