VulnerabilityPublished 26 Oct 2026

CVE-2026-115906: zip-rs zip2 · Improper Validation of Integrity Check Value

Affects zip-rs zip2Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 9.0.0 when convenient.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score

6.5Medium

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

Patch: Available – fixed in 9.0.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 zip-rs zip2 to 9.0.0.

Affected software

Product	Affected	Fixed in
zip-rszip2	Affected >=0.6.0 <9.0.0	Fixed in 9.0.0

AI-suggested

Upgrade to zip-rs zip2 version 9.0.0 or later, where this vulnerability is fixed. No other mitigation is indicated or required as the fix is available.

Description

A vulnerability in the zip-rs zip2 Rust library versions from 0.6.0 up to but not including 9.0.0 allows improper validation of the AES entry reader's HMAC authentication tag. Under certain conditions, such as when the encrypted entry has no payload or the data counter does not reach zero before the end of the archive, the reader may return a clean end of stream without verifying the authentication tag. This can cause applications using certain decryption methods to accept modified plaintext without detecting authentication errors. The issue is fixed in version 9.0.0.

Impact

This vulnerability allows an attacker to modify the plaintext of encrypted ZIP entries without detection by bypassing the HMAC authentication check under specific conditions. This compromises the integrity of the decrypted data, potentially leading to undetected data tampering. There is no impact on confidentiality or availability reported. The CVSS v3.1 score is 6.5 (medium severity) with an impact primarily on integrity.

Summary

The zip-rs zip2 library for Rust, versions >=0.6.0 and <9.0.0, contains a vulnerability in its AES entry reader (src/aes.rs) where the HMAC verification is only performed when the attacker-controlled data counter reaches zero. If the underlying reader reaches the real end of the archive while data_remaining is still positive, or if an encrypted entry has no payload, the authentication tag is not read or compared. Consequently, applications using by_index_decrypt, by_name_decrypt, by_path_decrypt, or password-enabled by_index_with_options may accept tampered plaintext without triggering an authentication error. This flaw is addressed in version 9.0.0.

CWE-354Improper Validation of Integrity Check Value (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.
Implementation
Ensure that the checksums present in messages are properly checked in accordance with the protocol specification before they are parsed and used.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
Attack patterns
Checksum Spoofing (opens in a new tab)
Padding Oracle Crypto Attack (opens in a new tab)
Manipulating Writeable Configuration Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1284Improper Validation of Specified Quantity in Input (opens in a new tab)
Base weakness
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
Implementation · Input Validation
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.
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).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 16:53 UTC

WeaknessesCWE-354, CWE-1284

Technical details

References

Community reviews

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