TLS ClientHello (JA4)

t13d1516h2_8daaf6152771_fe7c3632a08d

first seen 2026-08-28 13:11 · last seen 2026-09-24 13:11 · JSON

Inconsistencies

User-Agents observed with this fingerprint that contradict what it proves at the wire. all inconsistencies →

fingerprint User-Agent claims wire shows confidence seen first seen last seen

t13d1516h2_8daaf6152771_fe7c3632a08d

Mozilla/5.0 (X11; Linux x86_64; rv:154.0) Gecko/…

User-Agent claims Firefox 154.0

TLS extensions or signature algorithms differ from every measured Firefox capture

The cipher suites match Firefox, but the extension set or signature algorithms differ from every capture even after normalizing handshake-variant extensions. Most likely a field-trial, ECH, or build variant the catalog has not captured; occasionally mimicry. This sharpens as catalog coverage grows.

Full User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:154.0) Gecko/20100101 Firefox/154.0
Claimed version	154.0
Measured versions	146.0.1, 154.0, 140.0.2, 157.0.1, 151.0.2, 155.0, 153.0.3, 142.0.1, 153.0.4, 152.0.6, 150.0.2, 135.0, 156.0.1, 132.0, 152.0.3, 141.0, 153.0, 151.0.3, 156.0, 152.0.4, 151.0, 152.0.1, 151.0.4, 139.0, 153.0.1, 158.0.1, 152.0.5, 157.0, 158.0, 148.0.2, 137.0, 155.0.1, 144.0.2, 154.0.1, 134.0
Layer	cipher suites match; extension set or signature algorithms differ
JA4 label	unlabeled

low

2026-08-28

t13d1516h2_8daaf6152771_fe7c3632a08d

Mozilla/5.0 (X11; Linux x86_64; rv:155.0) Gecko/…

User-Agent claims Firefox 155.0

TLS extensions or signature algorithms differ from every measured Firefox capture

Full User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:155.0) Gecko/20100101 Firefox/155.0
Claimed version	155.0
Measured versions	146.0.1, 154.0, 140.0.2, 157.0.1, 151.0.2, 155.0, 153.0.3, 142.0.1, 153.0.4, 152.0.6, 150.0.2, 135.0, 156.0.1, 132.0, 152.0.3, 141.0, 153.0, 151.0.3, 156.0, 152.0.4, 151.0, 152.0.1, 151.0.4, 139.0, 153.0.1, 158.0.1, 152.0.5, 157.0, 158.0, 148.0.2, 137.0, 155.0.1, 144.0.2, 154.0.1, 134.0
Layer	cipher suites match; extension set or signature algorithms differ
JA4 label	unlabeled

low

2026-09-24

Decomposed attributes

Protocol	`t (TLS over TCP)`
TLS version	`13`
SNI	`d (domain)`
Cipher count	`15`
Extension count	`16`
ALPN	`h2`
Ciphers	`002f, 0035, 009c, 009d, 1301, 1302, 1303, c013, c014, c02b, c02c, c02f, c030, cca8, cca9`
Extensions	`0005, 000a, 000b, 000d, 0012, 0017, 001c, 0022, 0023, 002b, 002d, 0033, fe0d, ff01`
Signature algorithms	`0403, 0503, 0603, 0804, 0805, 0806, 0401, 0501, 0601`
JA4_r	`t13d1516h2_002f,0035,009c,009d,1301,1302,1303,c013,c014,c02b,c02c,c02f,c030,cca8,cca9_0005,000a,000b,000d,0012,0017,001c,0022,0023,002b,002d,0033,fe0d,ff01_0403,0503,0603,0804,0805,0806,0401,0501,0601`
JA4_o (sample)	`t13d1516h2_77608d807651_1bfb83dbd1af`
JA4_ro (sample)	`t13d1516h2_1301,1303,1302,c02b,c02f,cca9,cca8,c02c,c030,c013,c014,009c,009d,002f,0035_0000,0017,ff01,000a,000b,0023,0010,0005,0022,0012,0033,002b,000d,002d,001c,fe0d_0403,0503,0603,0804,0805,0806,0401,0501,0601`

Co-observed signals

Signals from other families seen in the same observation. A fingerprint spread thinly across many lower-layer signatures is a classic inconsistency signal.

HTTP request (JA4H)

fingerprint	co-occurrences
`ge20nr12enus_1204b4dfdccd_000000000000_000000000000`	2

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`1:65536;2:0;4:131072;5:16384\|12517377\|3:0:0:22\|m,p,a,s` Match?Exact match in Thumbprint's published controlled catalog captures: firefox 153.0, firefox 153.0.3, firefox 155.0.1, +31 more.The fingerprint page shows the full measured match list. More on the catalog.	2

TCP SYN (p0f)

fingerprint	co-occurrences
`4:53+11:0:1460:mss*44,10:mss,sok,ts,nop,ws:df,id+:0`	1
`4:55+9:0:1452:mss*44,10:mss,sok,ts,nop,ws:df,id+:0`	1

TCP SYN (JA4T)

fingerprint	co-occurrences
`64240_2-4-8-1-3_1460_10`	1
`64240_2-4-8-1-3_1452_10`	1

User-Agent

fingerprint	co-occurrences
`Mozilla/5.0 (X11; Linux x86_64; rv:154.0) Gecko/20100101 Firefox/154.0`	1
`Mozilla/5.0 (X11; Linux x86_64; rv:155.0) Gecko/20100101 Firefox/155.0`	1

Country

fingerprint	co-occurrences
`DE` · Germany	1
`US` · United States	1

Network (ASN)

fingerprint	co-occurrences
`AS3320` · Deutsche Telekom AG	1
`AS3737` · PenTeleData Inc.	1

Cross-transport links

TLS ClientHello fingerprints observed from the same client via the beacon's correlation id on the other transport (e.g. this stack over TCP ↔ that stack over QUIC).

fingerprint	linked observations
`q13d0315h3_55b375c5d22e_78345df32b3a`	2