VulnerabilityPublished 21 Oct 2026Updated 10 Nov 2026

CVE-2026-112902: Pillow · Memory disclosure and segfault in libtiff encoder via crafted TIFF tags

Affects PillowSource GCVE Database

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Authoritative record:CVE-2026-112902· High 8.3

Not known to be exploited · CVSS 8.3 High : upgrade to 13.0.0 soon.

Data as of 10 Nov 2026, 20:05 UTC

CVSS 4.0 base score

8.3High

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	8.3

Patch: Available – fixed in 13.0.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/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: None
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: None: There is no loss of integrity within 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 5 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 10 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 >=5.4.0 <13.0.0	Fixed in 13.0.0

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Description

``` ============================================================================ Memory disclosure and segfault in libtiff encoder via crafted TIFF tags Location: src/encode.c:1014 in PyImaging_LibTiffEncoderNew() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` A crafted TIFF file of a few hundred bytes makes Pillow copy an attacker-chosen amount of its own process memory into the TIFF it writes back out, or crash the process outright. The trigger is an ordinary `Image.open()` followed by a bare `im.save(fp, "TIFF")`. The only precondition is that the application re-saves images as TIFF. When the uploaded file is compressed, Pillow routes that save through libtiff automatically, with no options from the application. The attached reproducer does this with a 356-byte LZW TIFF: one crafted tag comes back holding 65536 bytes taken from `_imaging.so`'s read-only data, and a second crafted tag makes the worker die with SIGSEGV on every run. The bug is in `PyImaging_LibTiffEncoderNew` (`src/encode.c`). It decides what arguments to pass to the variadic `TIFFSetField()` from the shape of the Python value (scalar, tuple or bytes). It assumes its `ImagingLibTiffMergeFieldInfo()` call defined how libtiff will read them. But `TIFFMergeFieldInfo()` never overrides libtiff's built-in field table, so libtiff reads the arguments according to its own definition of the tag: - For a counted array tag such as DNGPrivateData (50740), a count-1 integer in the source file is taken as the byte count. The data pointer is then read from an argument slot Pillow never wrote, and that many bytes are copied into the output. - For a fixed-size array tag such as ActiveArea (50829), the integer itself is used as the source address. Where that unwritten slot points depends on the compiler. In the tested clang build it points into `_imaging.so`, and a larger count returned thousands of pointers into libpython, libc and libtiff, which defeats address-space randomisation for anyone chaining another bug. When the application preserves metadata with `tiffinfo=im.tag_v2`, a 64-bit entry turns ActiveArea into a 16-byte read from an address the attacker chooses. All observed memory errors are reads; no out-of-bounds write was found. Other branches of the same loop share the defect and are reachable from crafted TIFFs or from EXIF in JPEG/PNG/WebP re-saved as compressed TIFF. These are the `bytes`, RATIONAL-tuple and typed-tuple branches, and a BYTE-typed ColorMap. The file-reachable forwarding was introduced in `a3d45e9cefd0` ("Added custom int and float TIFF tags") and first released in 5.4.0. ## Details `PyImaging_LibTiffEncoderNew` (`src/encode.c:777-1060`) chooses the argument list it hands to the variadic `TIFFSetField()` from the *Python* value of each tag — scalar vs. tuple vs. `bytes`, and a type that is either autodetected or copied from the source file's IFD — and assumes that its own `ImagingLibTiffMergeFieldInfo()` registration defines how libtiff will read the `va_list`. It does not: libtiff keeps its built-in definition for every tag it already knows, and core tags are never registered at all. libtiff therefore consumes the varargs as `(count, pointer)`, `(pointer)` or three pointers according to *its* field table, whatever Pillow actually pushed. The encoder never consults that table (`TIFFFindField` / `TIFFFieldPassCount` / `TIFFFieldWriteCount` / `TIFFFieldDataType`) before the call. The most severe instance, and the one the attached reproducer exercises: when a TIFF is re-saved through the libtiff writer, every tag of the source IFD that Pillow does not recognise is forwarded to libtiff with `TIFFSetField()`. A count-1 integer entry is passed as a single scalar vararg. If libtiff's own field table defines that tag number as an *array* field, libtiff consumes the varargs as `(count, pointer)` or `(pointer)` instead, so the attacker's integer becomes either the number of bytes to copy from a never-written vararg slot, or the source address itself. The same mismatch is reachable through the typed tuple branches (tuple length consumed as a pointer for fixed-count built-in tags such as `CFARepeatPatternDim`, even when the source file is well-formed), the `bytes`, `TIFF_RATIONAL`-tuple and core-tag branches of the same loop; those are listed under *Other branches with the same defect* below and need to be covered by the same fix. A 181-byte TIFF (16×16 RGB, one LZW strip, plus one extra IFD entry `50740 / LONG / count 1 / value 4096` — DNGPrivateData) opened with `Image.open()` and saved with a bare `im.save(buf, "TIFF")` produces a 4296-byte output whose tag 50740 holds 4096 bytes that occur nowhere in the input; scanning `/proc/self/mem` finds them in the read-only data segment of `_imaging.so`. Changing the extra entry to `50829 / LONG / 1 / 64` (ActiveArea) makes the same two calls segfault in `memcpy(dst, src=0x40, n=16)` under `ImagingLibT

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Description

WeaknessesCWE-686

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