VulnerabilityPublished 12 Nov 2026

CVE-2026-128067: Pillow · Heap buffer overflow saving TIFF with libtiff when tags override image size

Affects PillowSource GCVE Database

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Authoritative record:CVE-2026-128067· High 8.4

Not known to be exploited · CVSS 8.4 High : upgrade to 13.0.0 soon.

Data as of 13 Nov 2026, 00:06 UTC

CVSS 4.0 base score

8.4High

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	8.4

Patch: Available – fixed in 13.0.0

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: Low
Vulnerable system availability: High
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: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
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 12 Nov 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 12 Nov 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

Upgrade Pillow to 13.0.0.

Affected software

Product	Affected	Fixed in
PyPIPillow	Affected <13.0.0	Fixed in 13.0.0

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

Description

``` ============================================================================ ANT-2026-CS7N494P [high] CWE-787 memory-safety Heap buffer overflow saving TIFF with libtiff when tags override image size Location: src/libImaging/TiffDecode.c:1035 in ImagingLibTiffEncode() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` When Pillow saves an image as a compressed TIFF, size information taken from the image's metadata can make the encoder read past the end of a heap buffer. Someone who uploads an image can use this to get the server process's memory, including pointers, copied into the saved file, or to crash the process. When the metadata also enables TIFF "Predictor=2" compression, the encoder writes past the buffer instead, corrupting the heap and aborting the process. This affects applications that write TIFF through libtiff (any `compression=` other than raw) and either carry the source metadata across with `exif=im.getexif()` / `tiffinfo=`, or simply re-save a crafted palette TIFF with `Image.open(f).save(out, "TIFF")`, which inherits its compression and predictor from the upload. In `TiffImagePlugin._save`'s libtiff branch, only `BitsPerSample` is pinned to the real image when the tag list for the encoder is built (`src/PIL/TiffImagePlugin.py:1955`). `ImageWidth`, `ImageLength` and `PlanarConfiguration` are set from `im.size` but are then overwritten by the `exif=`/`tiffinfo=` merge loop at `:1768-1772`. `SamplesPerPixel` is never set for single-band modes, so a value from the caller's tags or from the source TIFF's own IFD reaches `TIFFSetField`. `ImagingLibTiffEncode` then passes a row buffer sized from the actual image (`src/encode.c:291`) to `TIFFWriteScanline` (`src/libImaging/TiffDecode.c:1035`) with no check against `TIFFScanlineSize()`, and libtiff consumes a full scanline of the tag-described width from it. The attached reproducer demonstrates the read case. A 64x4 greyscale JPEG whose EXIF says `SamplesPerPixel=3, Photometric=RGB` is converted into a valid RGB TIFF in which 128 bytes of each row are live heap, including pointers that change from run to run. The same JPEG with EXIF `ImageWidth=2**27` kills the process with SIGSEGV. For the write case, the values written are byte-wise differences of existing heap contents rather than attacker-chosen data, and nothing beyond the observed glibc abort is shown. The `tiffinfo=` route dates back to Pillow 2.3.0 (`dbf47837ce99`), and the `exif=` route to 8.4.0 (`c0f619384cbc`). ## Details When an image is saved as TIFF through the libtiff encoder (any `compression=` other than raw, or `TiffImagePlugin.WRITE_LIBTIFF`), libtiff sizes its scanline from the `ImageWidth` / `SamplesPerPixel` / `BitsPerSample` / `PlanarConfiguration` tags it was handed, Pillow sizes the encoder row buffer from the real image, and nothing compares the two. In `TiffImagePlugin._save`'s libtiff branch only `BitsPerSample` is pinned in the attribute dict given to the encoder (`atts`, `src/PIL/TiffImagePlugin.py:1955-1982`); the other geometry tags can come from caller- or attacker-supplied data: - `ImageWidth` (256), `ImageLength` (257) and `PlanarConfiguration` (284) are set from `im.size` *before* the `tiffinfo=` / `exif=` merge loop at `:1768-1772`, so they are overwritten by it — by the EXIF of an uploaded JPEG, or by stale geometry in `im.getexif()` / `im.tag_v2` of a TIFF that Pillow auto-transposed on load (Orientation tag) or that the application `thumbnail()`ed. - `SamplesPerPixel` (277) is only put in the IFD for multi-band modes (`:1847-1850`), so for single-band images (`L`, `P`, `I;16`, `1`, …) a value from `exif=` / `tiffinfo=`, or from the *source TIFF's own IFD* via `supplied_tags` (`im.tag_v2`, `:1782`), is forwarded to libtiff. A palette TIFF with `SamplesPerPixel=2, BitsPerSample=(8,8), ExtraSamples=(0,)` opens as mode `P` (rawmode `PX`, extra sample dropped), and a bare `im.save(out, "TIFF")` — no save arguments; `compression` and `Predictor` are inherited from the source — already makes libtiff process `2*width` bytes per row from a `width`-byte buffer. `ImagingLibTiffEncode` then hands the image-sized row buffer to `TIFFWriteScanline`, and libtiff reads one scanline of the *tag-described* geometry out of a buffer holding one row of the *actual* image. With `Predictor = 2` (also forwarded from `tiffinfo=` / `im.tag_v2`) libtiff's horizontal differencing first rewrites the whole scanline **in place**, so the over-read becomes an out-of-bounds heap **write** on every row. The tags do not have to be supplied deliberately by the application: `im.getexif()` of an uploaded JPEG returns whatever IFD0 tags the file carries, and the common metadata-preserving conversion ```python im = Image.open(uploaded_jpeg) # 64x4, mode "L" im.save(out, "TIFF", exif=im.getexif(), compression="tiff_lzw") ``` behaves as follows on the stock build at thi

CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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What to do

Affected software

Description

WeaknessesCWE-787

Technical details

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