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GHSA-cmcx-xhr8-3w9p

MediumCVSS 5.7 / 10
Published Feb 20, 2020·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

Impact

Some regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings.

Patches

Please update uap-core to >= v0.7.3

Downstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.

Details

Each vulnerable regular expression reported here contains 3 overlapping capture groups. Backtracking has approximately cubic time complexity with respect to the length of the user-agent string.

Regex 1:

\bSmartWatch *\( *([^;]+) *; *([^;]+) *;

is vulnerable in portion *([^;]+) * and can be attacked with

"SmartWatch(" + (" " * 3500) + "z"

e.g.

SmartWatch(                                   z

Regex 2:

; *([^;/]+) Build[/ ]Huawei(MT1-U06|[A-Z]+\d+[^\);]+)[^\);]*\)

is vulnerable in portion \d+[^\);]+[^\);]* and can be attacked with

";A Build HuaweiA" + ("4" * 3500) + "z"

Regex 3:

(HbbTV)/[0-9]+\.[0-9]+\.[0-9]+ \([^;]*; *(LG)E *; *([^;]*) *;[^;]*;[^;]*;\)

is vulnerable in portion *([^;]*) * and can be attacked with

"HbbTV/0.0.0 (;LGE;" + (" " * 3500) + "z"

Regex 4:

(HbbTV)/[0-9]+\.[0-9]+\.[0-9]+ \([^;]*; *(?:CUS:([^;]*)|([^;]+)) *; *([^;]*) *;.*;

is vulnerable in portions *(?:CUS:([^;]*)|([^;]+)) * and *([^;]*) * and can be attacked with

"HbbTV/0.0.0 (;CUS:;" + (" " * 3500) + "z"
"HbbTV/0.0.0 (;" + (" " * 3500) + "z"
"HbbTV/0.0.0 (;z;" + (" " * 3500) + "z"

Reported by Ben Caller @bcaller

Risk Scores
Base Score
5.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
5.2

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
2.26%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Medium severity
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