CVE-2015-2688

buf_pullup in Tor before 0.2.4.26 and 0.2.5.x before 0.2.5.11 does not properly handle unexpected arrival times of buffers with invalid layouts, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via crafted packets.

Published: 2020-01-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2015-2688 is rated Moderate Risk (59.7/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.19%). EPSS rose +1.73% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2015-2688

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.45% 2.19% +1.73%
2 2026-04-22 0.57% 0.45% -0.12%
3 2025-03-30 — 0.57% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2015-2688

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2015-2688

OS Trackers for CVE-2015-2688

vendor priority summary link
debian not yet assigned CVE-2015-2688 not yet assigned priority: Debian including 1 source packages (tor), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2015-2688
ubuntu low CVE-2015-2688 low priority: Ubuntu including 1 source packages (tor), 10 status rows across 10 suites (lucid, precise, trusty, upstream, utopic, vivid, wily, xenial, yakkety, zesty): not-affected 4, released 3, ignored 2, DNE 1. https://ubuntu.com/security/CVE-2015-2688

Affected software / configurations for CVE-2015-2688

Vendor Product Version Raw CPE
torproject tor < 0.2.4.26 cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*
torproject tor >= 0.2.5.1, < 0.2.5.11 cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*

References for CVE-2015-2688

cvelogic Threat Intelligence