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CVE-2026-81928— Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record

Quick assessment

Affected
CVE-2026-81928
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

以下是该漏洞描述的中文翻译： Net::DNS 库（Perl）在 1.57 版本之前存在内存耗尽漏洞，原因是 函数在处理包含位置错误的 TSIG 记录的报文时，会因无限递归而导致内存被耗尽。 通过重新编码报文来对其进行签名，并且仅从“附加节”中移除 TSIG 记录。如果 TSIG 记录被解码到“回答节”或“授权节”，该记录在上述步骤中会被保留并再次被签名，因此再次调用 时缺乏终止条件，从而引发无限递归。 在解码过程中，系统不会直接拒绝此类报文：位于报文末尾之外的 TSIG 记录会触发“TSIG 位置错误或损坏”的错

AI Predicted 5.3 Difficulty: Moderate EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
None None < 1.57 affected

I. Basic Information for CVE-2026-81928

Vulnerability Information
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Vulnerability Title
Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record
Source: CVE Program / CVE List V5
Vulnerability Description
Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record. sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped. The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response. Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
未经控制的递归
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
- - 0 ~ 1.57 -

II. Public POCs for CVE-2026-81928

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III. Intelligence Information for CVE-2026-81928

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Vendor Pages for CVE-2026-81928 (2)

Other References for CVE-2026-81928 (1)

IV. Related Vulnerabilities

Same weakness: CWE-674

V. Comments for CVE-2026-81928

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