Unrated

Heap buffer overflow in pymonocypher argon2i_32

IdentifiersCVE-2026-53720CWE-122

CVE-2026-53720 is a heap buffer overflow vulnerability in pymonocypher affecting the argon2i_32 function. The flaw is caused by missing validation that the caller-supplied nb_blocks buffer is large enough before the function writes to it. When a buffer smaller than required is provided, argon2i_32 can write past the end of the allocated heap buffer, resulting in out-of-bounds memory corruption. The issue arises from improper bounds checking on a size-sensitive output or working buffer used by the Argon2i implementation.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can cause heap memory corruption through an out-of-bounds write. Depending on allocator behavior, memory layout, and application context, this may lead to process crashes, denial of service, data corruption, or potentially arbitrary code execution. At minimum, the vulnerability can destabilize applications that invoke the affected function with an undersized buffer.

Mitigation

If you can’t patch tonight, do this now.

Ensure that any call to argon2i_32 supplies an nb_blocks buffer sized according to the API's documented requirements. Where immediate patching is not possible, add defensive validation in calling code to reject undersized buffers before invoking the vulnerable function, and avoid exposing attacker-controlled inputs that can influence buffer sizing.

Remediation

Patch, then assume compromise.

Upgrade pymonocypher to version 4.0.2.8 or later, which adds validation to ensure the nb_blocks buffer is sufficiently large before use. Verify that all deployments and bundled dependencies are updated to a fixed release.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

No public activity tracked yet. Mallory keeps watching.

0 SOURCESView more in app

No public activity observed for this vulnerability.

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Exposure mapping

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Threat actor evidence

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Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity