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CVE-2026-68511— Paaster: TOCTOU race condition defeats the 'burn after reading' guarantee on view-once pastes

Quick assessment

Affected
WardPearce paaster
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.

Paaster 是一款剪贴板（pastebin）应用。在 3.3.0 版本之前，Paaster 的“仅查看一次”（阅后即焚）粘贴模式可通过并发请求被绕过。原本用于强制单次使用的检查机制是“先执行普通读操作，再执行独立的写操作”，该过程缺乏原子性，因此多个同时发起的请求都可能看到该粘贴内容为“尚未被阅读”，并都能成功获取其内容。此问题已在 3.3.0 版本中修复。

CVSS 6.3 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-68511

Vulnerability Information
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Vulnerability Title
Paaster: TOCTOU race condition defeats the 'burn after reading' guarantee on view-once pastes
Source: CVE Program / CVE List V5
Vulnerability Description
Paaster is a pastebin application. Prior to version 3.3.0, Paaster's "view once" (burn-after-reading) paste mode can be bypassed with concurrent requests. The check that's supposed to enforce single-use is a plain read followed by a separate write, with no atomicity, so multiple simultaneous requests can all see the paste as "not yet read" and all successfully retrieve it. This issue has been patched in version 3.3.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
WardPearce paaster < 3.3.0 -

II. Public POCs for CVE-2026-68511

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III. Intelligence Information for CVE-2026-68511

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Other References for CVE-2026-68511 (2)

IV. Related Vulnerabilities

Same product: paaster
Same vendor: WardPearce
Same weakness: CWE-362