VulnerabilityPublished 21 Oct 2026Updated 29 Oct 2026

CVE-2026-112897: Pillow · TiffDecode returns uninitialized memory as pixels for short JPEG strips

Affects aiderSource GCVE Database

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Authoritative record:CVE-2026-112897· High 8.7

Not known to be exploited · CVSS 8.7 High.

Data as of 30 Oct 2026, 07:30 UTC

CVSS 4.0 base score

8.7High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 4.0	8.7

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Homebrewaider`pkg:brew/aider`Other threats	Affected >=0.86.1_1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

``` ============================================================================ TiffDecode returns uninitialized memory as pixels for short JPEG strips Location: src/libImaging/TiffDecode.c:554 in _decodeStrip() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` Pillow hands back leftover process memory as image pixels when it opens a small crafted TIFF file. Anyone who can get an application to open their image, and can see something produced from its pixels (a thumbnail, a preview, a converted copy), can read heap memory that the process had previously used and freed. This works in the default configuration: opening and loading the 478-byte file succeeds with no error or warning, and every row below the first eight holds stale memory instead of picture content. The bug is in `_decodeStrip()` in `src/libImaging/TiffDecode.c`, and `_decodeTile()` has the same shape. The function `realloc()`s `state->buffer` to `TIFFStripSize()` bytes without initialising it and calls `TIFFReadEncodedStrip()`. Whenever that call does not return -1, it copies all `RowsPerStrip` rows of the buffer into the image. libtiff's JPEG codec only warns when the JPEG embedded in a strip has fewer rows than the strip, and Pillow silences libtiff warnings. The codec decodes the rows that exist and still returns the full strip size, so the untouched remainder is copied out as pixels. libtiff's Group 4 fax codec behaves the same way for a stream that ends early. The attached reproducer builds a 256×256 TIFF whose single strip or tile is a 256×8 JPEG. Before loading it, the script frees buffers filled with `b"LEAK"`. It then finds 15,872 copies of `LEAK` in rows 8–255 of the decoded image (the same freed chunk was reused in 500 of 500 runs). Under glibc's `MALLOC_PERTURB_`, those rows are entirely the allocator's fill byte. A well-formed control file decodes correctly in both cases. This is a read of uninitialised heap memory, not memory corruption. Each strip can disclose up to width × `RowsPerStrip` bytes, and what comes back depends on the allocator's state at the time. The strip path was introduced in e91b851fdc1c ("Add reading old-JPEG compressed TIFFs", first released in Pillow 6.0.0). The tile path has had the same pattern since f0436a4ddc95 (Pillow 5.3.0). ## Details `src/libImaging/TiffDecode.c` decodes compressed TIFFs through libtiff into a strip (or tile) buffer that it `realloc()`s to `TIFFStripSize()` bytes and never initialises, and then copies all `RowsPerStrip` rows of that buffer into the image whenever `TIFFReadEncodedStrip()` does not return -1. libtiff's JPEG codec does not fail when the JPEG stream inside a strip has fewer rows than the strip: it decodes the rows that exist and returns the full strip size. The rows it did not write are whatever the heap held before, and Pillow returns them as pixels. A 478-byte file shows it: a classic little-endian TIFF, 256×256, `BitsPerSample=8`, `Compression=7`, `PhotometricInterpretation=1`, `RowsPerStrip=256`, one strip whose data is a baseline JPEG of 256×**8** pixels (as written by `Image.new("L",(256,8),200).save(…,"JPEG")`). `Image.open(BytesIO(data)).load()` succeeds with default settings (compressed TIFFs always take the libtiff path). Rows 0–7 of the result are the JPEG content (value 200); the remaining 63488 bytes of `im.tobytes()` are heap garbage: run under glibc's `MALLOC_PERTURB_=1` they are all `0xFE`, under `MALLOC_PERTURB_=170` all `0x55` (the fresh-`malloc` fill byte), and in a process that has just freed buffers containing `b"LEAK"` they contain 15872 copies of `LEAK`. Feeding the same file to libtiff 4.5.0 directly confirms the library side: `TIFFReadEncodedStrip(t, 0, buf, 65536)` prints `JPEGPreDecode: Warning, Improper JPEG strip/tile size, expected 256x256, got 256x8.`, returns 65536, and leaves 63488 of the 65536 buffer bytes untouched. Pillow installs `TIFFSetWarningHandler(NULL)` (`TiffDecode.c:682`), so the warning is not visible either. The strip path: ```c // src/libImaging/TiffDecode.c:552 /* realloc to fit whole strip */ /* malloc check above */ new_data = realloc(state->buffer, state->bytes); // state->bytes = TIFFStripSize() … state->buffer = new_data; for (; state->y < state->ysize; state->y += rows_per_strip) { … if (TIFFReadEncodedStrip( tiff, TIFFComputeStrip(tiff, state->y, plane), (tdata_t)state->buffer, strip_size ) == -1) { … return -1; } … // iterate over each row in the strip and stuff data into image for (strip_row = 0; strip_row < MIN((INT32)rows_per_strip, state->ysize - state->y); strip_row++) { … shuffler( (UINT8 *)im->image[state->y + state->yoff + s

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