GHSA-26w7-cxv4-gfx2

Astro: Remote code execution through AVIF image optimization

Critical npm

Severity: 9.8 / 10; Critical · CVSS 3.1
Exploit chance (EPSS): —; No score published
Known exploited: No; Not in CISA's catalog
Weakness: CWE-125 Out-of-bounds Read; CWE-787 Out-of-bounds Write
Fix: 7.2.8; Upgrade astro to this version or later

Description

A vulnerability in libheif, used by the default Sharp image service in Astro, can lead to remote code execution when a malicious AVIF image is optimized.

Projects are affected when an attacker can cause Astro to process an untrusted AVIF image.

The fix was released in Astro 7.2.8, which requires Sharp 0.35.4.

Affected versions

npm

Package	Vulnerable	Fixed in
astro	`< 7.2.8`	`7.2.8`
astro	`< 7.2.8`	`7.2.8`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

astro npm → `7.2.8`

npm

npm install astro@7.2.8

yarn

yarn add astro@7.2.8

pnpm

pnpm add astro@7.2.8

Severity breakdown

CVSS 3.1 9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Weakness

CWE-125: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How to prevent it

Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
Architecture and Design: Use a language that provides appropriate memory abstractions.

CWE-787: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How to prevent it

Requirements: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.
Operation, Build and Compilation: 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 checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
Implementation: Consider adhering to the following rules when allocating and managing an application's memory: Double check that the buffer is as large as specified. When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string. Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space. If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Operation, Build and Compilation: Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
Operation: Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].
Implementation: Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available.

References

Advisories

Fixes and patches

github.com/withastro/astro/commit/ecb4082131490b4fe9a56aa44fda84b54ef8967b

Packages

github.com/withastro/astro

Timeline

Sep 8, 2026 Published
Sep 8, 2026 Last updated by the source

Advisory	Severity	Why it's related
GHSA-98hj-9722-w3j8 Astro: Reflected/Stored XSS via unescaped <script>/<style> tag content in JSX/MDX rendering	Medium	Also affects astro
GHSA-mpr7-6m5w-76rw Astro: Arbitrary CSS injection in Astro View Transitions	Low	Also affects astro
GHSA-376h-93r7-7g6f Astro: Authorization bypass from missing path-segment boundary check when stripping the configured base	Medium	Also affects astro
GHSA-8mv7-9c27-98vc Astro: composable `astro/hono` pipeline bypasses `security.checkOrigin` when `middleware()` is absent or misordered	Medium	Also affects astro
GHSA-f48w-9m4c-m7f5 Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for CVE-2026-54298)	Medium	Also affects astro
GHSA-7pw4-f3q4-r2p2 Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands	Low	Also affects astro
GHSA-4g3v-8h47-v7g6 Astro: Reflected XSS via unescaped View Transition animation properties	Medium	Also affects astro
GHSA-vj59-8hwv-xxmv Astro: Authorization Bypass via Decode Iteration Limit and Rewrite Path Canonicalization Mismatch	High	Also affects astro

Credits: cn-panda

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