[amasen02]

Purpose

Fixes #56527

When handling images with malformed or corrupt EXIF segments (for example, an APP1 segment containing an invalid TIFF header), calls to Image.getexif() raise exceptions such as SyntaxError: not a TIFF file (header b'...' not valid) or Pillow internal parser errors.

While normalize_image in vllm/multimodal/image.py wraps ImageOps.exif_transpose in contextlib.suppress(Exception) to gracefully tolerate malformed metadata, MultiModalHasher.serialize_item previously called obj.getexif() directly without error handling in both the Image.Image and MediaWithBytes branches (vllm/multimodal/hasher.py). Because SyntaxError does not inherit from ValueError, this uncaught exception causes the API server request to abort with HTTP 500.

This PR introduces a dedicated helper _get_image_id_bytes() with safe exception handling:

• Reads the optional Image.ExifTags.Base.ImageID UUID tag inside a try ... except Exception: block.
• If EXIF parsing or header extraction fails for any reason, gracefully falls back to standard pixel hashing (for Image.Image) or original_bytes (for MediaWithBytes), matching the error tolerance of normalize_image.

Test Plan

Added unit test test_hash_image_malformed_exif in tests/multimodal/test_hasher.py:

• Constructs a JPEG containing a malformed APP1 EXIF segment with an invalid TIFF header.
• Verifies that MultiModalHasher.hash_kwargs("blake3", image=image) produces a valid hash without raising SyntaxError.
• Verifies that MediaWithBytes(image, data) wrapping the malformed image also serializes and hashes successfully.
• Verified existing test_hash_image_exif_id continues to pass and correctly extract valid UUID ImageIDs.

Run tests:

pytest tests/multimodal/test_hasher.py -k "test_hash_image_malformed_exif or test_hash_image_exif_id"

Test Result

tests/multimodal/test_hasher.py::test_hash_image_malformed_exif PASSED
tests/multimodal/test_hasher.py::test_hash_image_exif_id PASSED

Linting & formatting:

ruff check vllm/multimodal/hasher.py tests/multimodal/test_hasher.py
ruff format --check vllm/multimodal/hasher.py tests/multimodal/test_hasher.py

Output:

All checks passed!
2 files already formatted

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[github-actions]

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[DarkLight1337]

Thanks

[DarkLight1337]

/ci run

[github-actions]

✅ Triggered Buildkite CI #88535 for commit 4c588caca4ad.

[Hotragn]

The fix looks right to me, and I want to record why the new test is valid, because it is easy to glance at and think it is vacuous — I did at first.

On a freshly opened image this payload does not raise at all:

[A] image.getexif() on a fresh Image.open(...)   -> NO RAISE, returns {}
[B] ImageOps.exif_transpose() on a fresh image   -> NO RAISE
[C] suppressed exif_transpose(), then .load(),
    then getexif()                               -> SyntaxError: not a TIFF file
                                                    (header b'XXXX\x00\x00\x00\x08' not valid)

So the raise needs the earlier (suppressed) exif_transpose to have primed Pillow's lazy EXIF state first — which is exactly what ImageMediaIO.load_bytes does at vllm/multimodal/media/image.py:90-92 (normalize_image(image) → image.load() → _convert_image_mode(image)). That is the shape serialize_item sees in production, and it is what your test reproduces. .convert() carries the poisoned state forward too, so it survives the mode conversion. Pillow 12.3.0.

One call site still unguarded

While checking whether this was the only place, ImageOps.exif_transpose is called bare in the Molmo2 processor:

• vllm/model_executor/models/molmo2.py:1308 — inside that module's own exif_transpose() helper
• reached from get_image_replacement_molmo2 at vllm/model_executor/models/molmo2.py:2221

vllm/multimodal/image.py:normalize_image wraps its call in contextlib.suppress(Exception); molmo2's copy does not. Driving the same payload into exactly the state the connector hands the model processor:

img = Image.open(BytesIO(data))
with contextlib.suppress(Exception):          # normalize_image
    img = ImageOps.exif_transpose(img)
img.load()

ImageOps.exif_transpose(img)                  # molmo2.py:1308
# SyntaxError: not a TIFF file (header b'XXXX\x00\x00\x00\x08' not valid)

Same root cause and same uncaught-SyntaxError failure mode as #56527, just on the prompt-replacement path instead of the hashing path. Worth noting img.load() without the preceding suppressed transpose does not raise, which is probably why this one went unnoticed.

Happy either way on scope — it is a one-line contextlib.suppress in a single extra file if you would rather keep the class together in this PR and one CI run, and I am glad to send it as a follow-up instead once this lands. Not asking you to widen an approved PR if you would rather not.

For disclosure: I have an open PR (#54283) that reworks the framing inside serialize_item, so these two will conflict textually wherever lands second. Mine is the one that is blocked, so I will rebase onto yours — flagging it only so the conflict is not a surprise.

[DarkLight1337]

/ci retry

[github-actions]

✅ Triggered Buildkite CI #89282 for commit 27a04d99f847, running 5 failed step(s) from Buildkite CI #88535.

[Hotragn]

Follow-up as promised, now that this has landed: #57234.

Molmo 2 keeps its own copy of the EXIF normalization
(vllm/model_executor/models/molmo2.py:1302) and calls
ImageOps.exif_transpose bare, so for that model this fix moved the failure one
step later rather than removing it — hashing is now tolerant, and the same
payload then raises SyntaxError out of get_image_replacement_molmo2.
Confirmed against current main:

vllm/model_executor/models/molmo2.py:1302: in exif_transpose
    images = ImageOps.exif_transpose(images)
E  SyntaxError: not a TIFF file (header b'XXXX\x00\x00\x00\x08' not valid)

That is the last bare read — grep -rn "exif_transpose\|getexif" --include=*.py vllm/
returns only multimodal/image.py (suppressed), multimodal/hasher.py (yours),
and those molmo2 lines.

One detail from your test that is worth knowing if you touch this again: with
that payload Pillow raises only on the first read of the poisoned lazy EXIF
state and silently succeeds afterwards (measured on 12.3.0). So a test that
reuses one image object across cases passes on main by coincidence; #57234
loads a fresh one per assertion for that reason.