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CVE-2016-6354

Publication date 21 September 2016

Last updated 24 July 2024

Ubuntu priority

Low

Why this priority?

Cvss 3 Severity Score

9.8 · Critical

Score breakdown

Heap-based buffer overflow in the yy_get_next_buffer function in Flex before 2.6.1 might allow context-dependent attackers to cause a denial of service or possibly execute arbitrary code via vectors involving num_to_read.

Read the notes from the security team

Status

Package Ubuntu Release Status
flex 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Not affected
21.04 hirsute
Not affected
20.10 groovy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Not affected
18.10 cosmic
Not affected
18.04 LTS bionic
Not affected
17.10 artful
Not affected
17.04 zesty
Not affected
16.10 yakkety
Not affected
16.04 LTS xenial
Vulnerable
15.10 wily Ignored end of life
14.04 LTS trusty Not in release
12.04 LTS precise
Not affected

Notes

mdeslaur

introduced in 2.5.36 by https://github.com/westes/flex/commit/9ba3187a537d6a58d345f2874d06087fd4050399

sbeattie

redhat bug claims that it's not exploitable due to followup code also, simply replacing yy_size_t with int on num_to_read as in the upstream patch causes even more signed comparison warnings in flex generated sources; there's a comparison against a size_t variable in YY_INPUT for one. The "correct" fix for this likely includes the additional commit mentioned in the oss-security post. fixing will also require recompiling anything with generated code from the versions of flex in vivid through xenial.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
flex

Severity score breakdown

Parameter Value
Base score 9.8 · Critical
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H